Improve null-safety of module/spring-boot-actuator

See gh-46926

config/checkstyle/checkstyle-suppressions.xml

@@ -75,4 +75,5 @@
 	<suppress files="ConditionMessage\.java" checks="NoWhitespaceBefore" message="'...' is preceded with whitespace"/>
 	<suppress files="EntityManagerFactoryBuilder\.java" checks="NoWhitespaceBefore" message="'...' is preceded with whitespace"/>
 	<suppress files="DockerApi\.java" checks="NoWhitespaceBefore" message="'...' is preceded with whitespace"/>
+	<suppress files="InvocationContext\.java" checks="NoWhitespaceBefore" message="'...' is preceded with whitespace"/>
 </suppressions>

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/AuditEvent.java

@@ -53,7 +53,7 @@ public class AuditEvent implements Serializable {
 
 	private final String type;
 
-	private final Map<String, Object> data;
+	private final Map<String, @Nullable Object> data;
 
 	/**
 	 * Create a new audit event for the current time.
@@ -61,7 +61,7 @@ public class AuditEvent implements Serializable {
 	 * @param type the event type
 	 * @param data the event data
 	 */
-	public AuditEvent(String principal, String type, Map<String, Object> data) {
+	public AuditEvent(String principal, String type, Map<String, @Nullable Object> data) {
 		this(Instant.now(), principal, type, data);
 	}
 
@@ -83,7 +83,7 @@ public class AuditEvent implements Serializable {
 	 * @param type the event type
 	 * @param data the event data
 	 */
-	public AuditEvent(Instant timestamp, @Nullable String principal, String type, Map<String, Object> data) {
+	public AuditEvent(Instant timestamp, @Nullable String principal, String type, Map<String, @Nullable Object> data) {
 		Assert.notNull(timestamp, "'timestamp' must not be null");
 		Assert.notNull(type, "'type' must not be null");
 		this.timestamp = timestamp;
@@ -92,8 +92,8 @@ public class AuditEvent implements Serializable {
 		this.data = Collections.unmodifiableMap(data);
 	}
 
-	private static Map<String, Object> convert(String[] data) {
-		Map<String, Object> result = new HashMap<>();
+	private static Map<String, @Nullable Object> convert(String[] data) {
+		Map<String, @Nullable Object> result = new HashMap<>();
 		for (String entry : data) {
 			int index = entry.indexOf('=');
 			if (index != -1) {
@@ -135,7 +135,7 @@ public class AuditEvent implements Serializable {
 	 * Returns the event data.
 	 * @return the event data
 	 */
-	public Map<String, Object> getData() {
+	public Map<String, @Nullable Object> getData() {
 		return this.data;
 	}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/audit/listener/AuditApplicationEvent.java

@@ -19,6 +19,8 @@ package org.springframework.boot.actuate.audit.listener;
 import java.time.Instant;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.actuate.audit.AuditEvent;
 import org.springframework.context.ApplicationEvent;
 import org.springframework.util.Assert;
@@ -41,7 +43,7 @@ public class AuditApplicationEvent extends ApplicationEvent {
 	 * @param data the event data
 	 * @see AuditEvent#AuditEvent(String, String, Map)
 	 */
-	public AuditApplicationEvent(String principal, String type, Map<String, Object> data) {
+	public AuditApplicationEvent(String principal, String type, Map<String, @Nullable Object> data) {
 		this(new AuditEvent(principal, type, data));
 	}
 
@@ -66,7 +68,7 @@ public class AuditApplicationEvent extends ApplicationEvent {
 	 * @param data the event data
 	 * @see AuditEvent#AuditEvent(Instant, String, String, Map)
 	 */
-	public AuditApplicationEvent(Instant timestamp, String principal, String type, Map<String, Object> data) {
+	public AuditApplicationEvent(Instant timestamp, String principal, String type, Map<String, @Nullable Object> data) {
 		this(new AuditEvent(timestamp, principal, type, data));
 	}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/availability/AvailabilityStateHealthIndicator.java

@@ -45,7 +45,7 @@ public class AvailabilityStateHealthIndicator extends AbstractHealthIndicator {
 
 	private final Class<? extends AvailabilityState> stateType;
 
-	private final Map<AvailabilityState, Status> statusMappings = new HashMap<>();
+	private final Map<@Nullable AvailabilityState, Status> statusMappings = new HashMap<>();
 
 	/**
 	 * Create a new {@link AvailabilityStateHealthIndicator} instance.

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/beans/BeansEndpoint.java

@@ -29,6 +29,7 @@ import org.springframework.boot.actuate.endpoint.annotation.Endpoint;
 import org.springframework.boot.actuate.endpoint.annotation.ReadOperation;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.lang.Contract;
 import org.springframework.util.StringUtils;
 
 /**
@@ -56,7 +57,7 @@ public class BeansEndpoint {
 
 	@ReadOperation
 	public BeansDescriptor beans() {
-		Map<String, ContextBeansDescriptor> contexts = new HashMap<>();
+		Map<@Nullable String, ContextBeansDescriptor> contexts = new HashMap<>();
 		ConfigurableApplicationContext context = this.context;
 		while (context != null) {
 			contexts.put(context.getId(), ContextBeansDescriptor.describing(context));
@@ -79,13 +80,13 @@ public class BeansEndpoint {
 	 */
 	public static final class BeansDescriptor implements OperationResponseBody {
 
-		private final Map<String, ContextBeansDescriptor> contexts;
+		private final Map<@Nullable String, ContextBeansDescriptor> contexts;
 
-		private BeansDescriptor(Map<String, ContextBeansDescriptor> contexts) {
+		private BeansDescriptor(Map<@Nullable String, ContextBeansDescriptor> contexts) {
 			this.contexts = contexts;
 		}
 
-		public Map<String, ContextBeansDescriptor> getContexts() {
+		public Map<@Nullable String, ContextBeansDescriptor> getContexts() {
 			return this.contexts;
 		}
 
@@ -113,6 +114,7 @@ public class BeansEndpoint {
 			return this.beans;
 		}
 
+		@Contract("!null -> !null")
 		private static @Nullable ContextBeansDescriptor describing(@Nullable ConfigurableApplicationContext context) {
 			if (context == null) {
 				return null;

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/context/properties/ConfigurationPropertiesReportEndpoint.java

@@ -152,7 +152,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	private ConfigurationPropertiesDescriptor getConfigurationProperties(ApplicationContext context,
 			Predicate<ConfigurationPropertiesBean> beanFilterPredicate, boolean showUnsanitized) {
 		ObjectMapper mapper = getObjectMapper();
-		Map<String, ContextConfigurationPropertiesDescriptor> contexts = new HashMap<>();
+		Map<@Nullable String, ContextConfigurationPropertiesDescriptor> contexts = new HashMap<>();
 		ApplicationContext target = context;
 
 		while (target != null) {
@@ -221,8 +221,8 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	private ConfigurationPropertiesBeanDescriptor describeBean(ObjectMapper mapper, ConfigurationPropertiesBean bean,
 			boolean showUnsanitized) {
 		String prefix = bean.getAnnotation().prefix();
-		Map<String, Object> serialized = safeSerialize(mapper, bean.getInstance(), prefix);
-		Map<String, Object> properties = sanitize(prefix, serialized, showUnsanitized);
+		Map<String, @Nullable Object> serialized = safeSerialize(mapper, bean.getInstance(), prefix);
+		Map<String, @Nullable Object> properties = sanitize(prefix, serialized, showUnsanitized);
 		Map<String, Object> inputs = getInputs(prefix, serialized, showUnsanitized);
 		return new ConfigurationPropertiesBeanDescriptor(prefix, properties, inputs);
 	}
@@ -236,7 +236,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	 * @return the serialized instance
 	 */
 	@SuppressWarnings({ "unchecked" })
-	private Map<String, Object> safeSerialize(ObjectMapper mapper, @Nullable Object bean, String prefix) {
+	private Map<String, @Nullable Object> safeSerialize(ObjectMapper mapper, @Nullable Object bean, String prefix) {
 		try {
 			return new HashMap<>(mapper.convertValue(bean, Map.class));
 		}
@@ -254,11 +254,12 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	 * @return the sanitized map
 	 */
 	@SuppressWarnings("unchecked")
-	private Map<String, Object> sanitize(String prefix, Map<String, Object> map, boolean showUnsanitized) {
+	private Map<String, @Nullable Object> sanitize(String prefix, Map<String, @Nullable Object> map,
+			boolean showUnsanitized) {
 		map.forEach((key, value) -> {
 			String qualifiedKey = getQualifiedKey(prefix, key);
 			if (value instanceof Map) {
-				map.put(key, sanitize(qualifiedKey, (Map<String, Object>) value, showUnsanitized));
+				map.put(key, sanitize(qualifiedKey, (Map<String, @Nullable Object>) value, showUnsanitized));
 			}
 			else if (value instanceof List) {
 				map.put(key, sanitize(qualifiedKey, (List<Object>) value, showUnsanitized));
@@ -270,7 +271,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 		return map;
 	}
 
-	private @Nullable Object sanitizeWithPropertySourceIfPresent(String qualifiedKey, Object value,
+	private @Nullable Object sanitizeWithPropertySourceIfPresent(String qualifiedKey, @Nullable Object value,
 			boolean showUnsanitized) {
 		ConfigurationPropertyName currentName = getCurrentName(qualifiedKey);
 		ConfigurationProperty candidate = getCandidate(currentName);
@@ -309,13 +310,13 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	}
 
 	@SuppressWarnings("unchecked")
-	private List<Object> sanitize(String prefix, List<Object> list, boolean showUnsanitized) {
-		List<Object> sanitized = new ArrayList<>();
+	private List<@Nullable Object> sanitize(String prefix, List<Object> list, boolean showUnsanitized) {
+		List<@Nullable Object> sanitized = new ArrayList<>();
 		int index = 0;
 		for (Object item : list) {
 			String name = prefix + "[" + index++ + "]";
 			if (item instanceof Map) {
-				sanitized.add(sanitize(name, (Map<String, Object>) item, showUnsanitized));
+				sanitized.add(sanitize(name, (Map<String, @Nullable Object>) item, showUnsanitized));
 			}
 			else if (item instanceof List) {
 				sanitized.add(sanitize(name, (List<Object>) item, showUnsanitized));
@@ -328,12 +329,12 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	}
 
 	@SuppressWarnings("unchecked")
-	private Map<String, Object> getInputs(String prefix, Map<String, Object> map, boolean showUnsanitized) {
+	private Map<String, Object> getInputs(String prefix, Map<String, @Nullable Object> map, boolean showUnsanitized) {
 		Map<String, Object> augmented = new LinkedHashMap<>(map);
 		map.forEach((key, value) -> {
 			String qualifiedKey = getQualifiedKey(prefix, key);
 			if (value instanceof Map) {
-				augmented.put(key, getInputs(qualifiedKey, (Map<String, Object>) value, showUnsanitized));
+				augmented.put(key, getInputs(qualifiedKey, (Map<String, @Nullable Object>) value, showUnsanitized));
 			}
 			else if (value instanceof List) {
 				augmented.put(key, getInputs(qualifiedKey, (List<Object>) value, showUnsanitized));
@@ -352,7 +353,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 		for (Object item : list) {
 			String name = prefix + "[" + index++ + "]";
 			if (item instanceof Map) {
-				augmented.add(getInputs(name, (Map<String, Object>) item, showUnsanitized));
+				augmented.add(getInputs(name, (Map<String, @Nullable Object>) item, showUnsanitized));
 			}
 			else if (item instanceof List) {
 				augmented.add(getInputs(name, (List<Object>) item, showUnsanitized));
@@ -364,7 +365,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 		return augmented;
 	}
 
-	private Map<String, Object> applyInput(String qualifiedKey, boolean showUnsanitized) {
+	private Map<String, @Nullable Object> applyInput(String qualifiedKey, boolean showUnsanitized) {
 		ConfigurationPropertyName currentName = getCurrentName(qualifiedKey);
 		ConfigurationProperty candidate = getCandidate(currentName);
 		PropertySource<?> propertySource = getPropertySource(candidate);
@@ -377,8 +378,8 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 		return Collections.emptyMap();
 	}
 
-	private Map<String, Object> getInput(ConfigurationProperty candidate, @Nullable Object sanitizedValue) {
-		Map<String, Object> input = new LinkedHashMap<>();
+	private Map<String, @Nullable Object> getInput(ConfigurationProperty candidate, @Nullable Object sanitizedValue) {
+		Map<String, @Nullable Object> input = new LinkedHashMap<>();
 		Origin origin = Origin.from(candidate);
 		List<Origin> originParents = Origin.parentsFrom(candidate);
 		input.put("value", sanitizedValue);
@@ -511,7 +512,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 				@Nullable Constructor<?> constructor) {
 			if (constructor != null) {
 				Parameter[] parameters = constructor.getParameters();
-				@Nullable String[] names = PARAMETER_NAME_DISCOVERER.getParameterNames(constructor);
+				@Nullable String @Nullable [] names = PARAMETER_NAME_DISCOVERER.getParameterNames(constructor);
 				if (names == null) {
 					names = new String[parameters.length];
 				}
@@ -520,7 +521,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 						.get(Name.class)
 						.getValue(MergedAnnotation.VALUE, String.class)
 						.orElse((names[i] != null) ? names[i] : parameters[i].getName());
-					if (name.equals(writer.getName())) {
+					if (name != null && name.equals(writer.getName())) {
 						return true;
 					}
 				}
@@ -576,13 +577,13 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 	 */
 	public static final class ConfigurationPropertiesDescriptor implements OperationResponseBody {
 
-		private final Map<String, ContextConfigurationPropertiesDescriptor> contexts;
+		private final Map<@Nullable String, ContextConfigurationPropertiesDescriptor> contexts;
 
-		ConfigurationPropertiesDescriptor(Map<String, ContextConfigurationPropertiesDescriptor> contexts) {
+		ConfigurationPropertiesDescriptor(Map<@Nullable String, ContextConfigurationPropertiesDescriptor> contexts) {
 			this.contexts = contexts;
 		}
 
-		public Map<String, ContextConfigurationPropertiesDescriptor> getContexts() {
+		public Map<@Nullable String, ContextConfigurationPropertiesDescriptor> getContexts() {
 			return this.contexts;
 		}
 
@@ -621,11 +622,11 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 
 		private final String prefix;
 
-		private final Map<String, Object> properties;
+		private final Map<String, @Nullable Object> properties;
 
 		private final Map<String, Object> inputs;
 
-		private ConfigurationPropertiesBeanDescriptor(String prefix, Map<String, Object> properties,
+		private ConfigurationPropertiesBeanDescriptor(String prefix, Map<String, @Nullable Object> properties,
 				Map<String, Object> inputs) {
 			this.prefix = prefix;
 			this.properties = properties;
@@ -636,7 +637,7 @@ public class ConfigurationPropertiesReportEndpoint implements ApplicationContext
 			return this.prefix;
 		}
 
-		public Map<String, Object> getProperties() {
+		public Map<String, @Nullable Object> getProperties() {
 			return this.properties;
 		}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/InvocationContext.java

@@ -49,7 +49,7 @@ public class InvocationContext {
 	 * the operation.
 	 */
 	public InvocationContext(SecurityContext securityContext, Map<String, Object> arguments,
-			OperationArgumentResolver... argumentResolvers) {
+			OperationArgumentResolver @Nullable ... argumentResolvers) {
 		Assert.notNull(securityContext, "'securityContext' must not be null");
 		Assert.notNull(arguments, "'arguments' must not be null");
 		this.arguments = arguments;

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/OperationArgumentResolver.java

@@ -54,7 +54,7 @@ public interface OperationArgumentResolver {
 	 * @param supplier the value supplier
 	 * @return an {@link OperationArgumentResolver} instance
 	 */
-	static <T> OperationArgumentResolver of(Class<T> type, Supplier<? extends T> supplier) {
+	static <T> OperationArgumentResolver of(Class<T> type, Supplier<? extends @Nullable T> supplier) {
 		Assert.notNull(type, "'type' must not be null");
 		Assert.notNull(supplier, "'supplier' must not be null");
 		return new OperationArgumentResolver() {
@@ -66,7 +66,7 @@ public interface OperationArgumentResolver {
 
 			@Override
 			@SuppressWarnings("unchecked")
-			public <R> R resolve(Class<R> argumentType) {
+			public <R> @Nullable R resolve(Class<R> argumentType) {
 				return (R) supplier.get();
 			}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/ProducibleOperationArgumentResolver.java

@@ -37,13 +37,13 @@ import org.springframework.util.MimeTypeUtils;
  */
 public class ProducibleOperationArgumentResolver implements OperationArgumentResolver {
 
-	private final Supplier<List<String>> accepts;
+	private final Supplier<@Nullable List<String>> accepts;
 
 	/**
 	 * Create a new {@link ProducibleOperationArgumentResolver} instance.
 	 * @param accepts supplier that returns accepted mime types
 	 */
-	public ProducibleOperationArgumentResolver(Supplier<List<String>> accepts) {
+	public ProducibleOperationArgumentResolver(Supplier<@Nullable List<String>> accepts) {
 		this.accepts = accepts;
 	}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/SanitizableData.java

@@ -38,7 +38,7 @@ public final class SanitizableData {
 
 	private final @Nullable PropertySource<?> propertySource;
 
-	private final String key;
+	private final @Nullable String key;
 
 	private @Nullable String lowerCaseKey;
 
@@ -50,7 +50,7 @@ public final class SanitizableData {
 	 * @param key the data key
 	 * @param value the data value
 	 */
-	public SanitizableData(@Nullable PropertySource<?> propertySource, String key, @Nullable Object value) {
+	public SanitizableData(@Nullable PropertySource<?> propertySource, @Nullable String key, @Nullable Object value) {
 		this.propertySource = propertySource;
 		this.key = key;
 		this.value = value;
@@ -69,7 +69,7 @@ public final class SanitizableData {
 	 * Return the key of the data.
 	 * @return the data key
 	 */
-	public String getKey() {
+	public @Nullable String getKey() {
 		return this.key;
 	}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/SanitizingFunction.java

@@ -338,7 +338,7 @@ public interface SanitizingFunction {
 	 * @see #filter()
 	 * @see #sanitizeValue()
 	 */
-	default SanitizingFunction ifValueMatches(Predicate<Object> predicate) {
+	default SanitizingFunction ifValueMatches(Predicate<@Nullable Object> predicate) {
 		Assert.notNull(predicate, "'predicate' must not be null");
 		return ifMatches((data) -> predicate.test(data.getValue()));
 	}
@@ -373,12 +373,13 @@ public interface SanitizingFunction {
 	 */
 	default SanitizingFunction ifMatches(Predicate<SanitizableData> predicate) {
 		Assert.notNull(predicate, "'predicate' must not be null");
-		Predicate<SanitizableData> filter = (filter() != null) ? filter().or(predicate) : predicate;
+		Predicate<SanitizableData> filter = filter();
+		Predicate<SanitizableData> newFilter = (filter != null) ? filter.or(predicate) : predicate;
 		return new SanitizingFunction() {
 
 			@Override
 			public Predicate<SanitizableData> filter() {
-				return filter;
+				return newFilter;
 			}
 
 			@Override

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/annotation/EndpointDiscoverer.java

@@ -129,10 +129,12 @@ public abstract class EndpointDiscoverer<E extends ExposableEndpoint<O>, O exten
 
 	@Override
 	public final Collection<E> getEndpoints() {
-		if (this.endpoints == null) {
-			this.endpoints = discoverEndpoints();
+		Collection<E> endpoints = this.endpoints;
+		if (endpoints == null) {
+			endpoints = discoverEndpoints();
+			this.endpoints = endpoints;
 		}
-		return this.endpoints;
+		return endpoints;
 	}
 
 	private Collection<E> discoverEndpoints() {
@@ -149,10 +151,12 @@ public abstract class EndpointDiscoverer<E extends ExposableEndpoint<O>, O exten
 			if (!ScopedProxyUtils.isScopedTarget(beanName)) {
 				EndpointBean endpointBean = createEndpointBean(beanName);
 				EndpointBean previous = byId.putIfAbsent(endpointBean.getId(), endpointBean);
-				Assert.state(previous == null, () -> "Found two endpoints with the id '" + endpointBean.getId() + "': '"
+				if (previous != null) {
+					throw new IllegalStateException("Found two endpoints with the id '" + endpointBean.getId() + "': '"
 							+ endpointBean.getBeanName() + "' and '" + previous.getBeanName() + "'");
 				}
 			}
+		}
 		return byId.values();
 	}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/web/PathMappedEndpoints.java

@@ -28,6 +28,7 @@ import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.actuate.endpoint.EndpointId;
 import org.springframework.boot.actuate.endpoint.EndpointsSupplier;
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
@@ -167,6 +168,7 @@ public class PathMappedEndpoints implements Iterable<PathMappedEndpoint> {
 		return this.endpoints.values().iterator();
 	}
 
+	@Contract("!null -> !null")
 	private @Nullable String getPath(@Nullable PathMappedEndpoint endpoint) {
 		if (endpoint == null) {
 			return null;

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/env/EnvironmentEndpoint.java

@@ -113,22 +113,23 @@ public class EnvironmentEndpoint {
 	}
 
 	EnvironmentEntryDescriptor getEnvironmentEntryDescriptor(String propertyName, boolean showUnsanitized) {
-		Map<String, PropertyValueDescriptor> descriptors = getPropertySourceDescriptors(propertyName, showUnsanitized);
+		Map<String, @Nullable PropertyValueDescriptor> descriptors = getPropertySourceDescriptors(propertyName,
+				showUnsanitized);
 		PropertySummaryDescriptor summary = getPropertySummaryDescriptor(descriptors);
 		return new EnvironmentEntryDescriptor(summary, Arrays.asList(this.environment.getActiveProfiles()),
 				Arrays.asList(this.environment.getDefaultProfiles()), toPropertySourceDescriptors(descriptors));
 	}
 
 	private List<PropertySourceEntryDescriptor> toPropertySourceDescriptors(
-			Map<String, PropertyValueDescriptor> descriptors) {
+			Map<String, @Nullable PropertyValueDescriptor> descriptors) {
 		List<PropertySourceEntryDescriptor> result = new ArrayList<>();
 		descriptors.forEach((name, property) -> result.add(new PropertySourceEntryDescriptor(name, property)));
 		return result;
 	}
 
 	private @Nullable PropertySummaryDescriptor getPropertySummaryDescriptor(
-			Map<String, PropertyValueDescriptor> descriptors) {
-		for (Map.Entry<String, PropertyValueDescriptor> entry : descriptors.entrySet()) {
+			Map<String, @Nullable PropertyValueDescriptor> descriptors) {
+		for (Map.Entry<String, @Nullable PropertyValueDescriptor> entry : descriptors.entrySet()) {
 			if (entry.getValue() != null) {
 				return new PropertySummaryDescriptor(entry.getKey(), entry.getValue().getValue());
 			}
@@ -136,9 +137,9 @@ public class EnvironmentEndpoint {
 		return null;
 	}
 
-	private Map<String, PropertyValueDescriptor> getPropertySourceDescriptors(String propertyName,
+	private Map<String, @Nullable PropertyValueDescriptor> getPropertySourceDescriptors(String propertyName,
 			boolean showUnsanitized) {
-		Map<String, PropertyValueDescriptor> propertySources = new LinkedHashMap<>();
+		Map<String, @Nullable PropertyValueDescriptor> propertySources = new LinkedHashMap<>();
 		getPropertySourcesAsMap().forEach((sourceName, source) -> propertySources.put(sourceName,
 				source.containsProperty(propertyName) ? describeValueOf(propertyName, source, showUnsanitized) : null));
 		return propertySources;
@@ -335,9 +336,9 @@ public class EnvironmentEndpoint {
 
 		private final String name;
 
-		private final PropertyValueDescriptor property;
+		private final @Nullable PropertyValueDescriptor property;
 
-		private PropertySourceEntryDescriptor(String name, PropertyValueDescriptor property) {
+		private PropertySourceEntryDescriptor(String name, @Nullable PropertyValueDescriptor property) {
 			this.name = name;
 			this.property = property;
 		}
@@ -346,7 +347,7 @@ public class EnvironmentEndpoint {
 			return this.name;
 		}
 
-		public PropertyValueDescriptor getProperty() {
+		public @Nullable PropertyValueDescriptor getProperty() {
 			return this.property;
 		}
 

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/HealthEndpointGroups.java

@@ -83,7 +83,8 @@ public interface HealthEndpointGroups {
 		Set<HealthEndpointGroup> filteredGroups = new LinkedHashSet<>();
 		getNames().stream()
 			.map(this::get)
-			.filter((group) -> group.getAdditionalPath() != null && group.getAdditionalPath().hasNamespace(namespace))
+			.filter((group) -> group != null && group.getAdditionalPath() != null
+					&& group.getAdditionalPath().hasNamespace(namespace))
 			.forEach(filteredGroups::add);
 		return filteredGroups;
 	}

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/SimpleStatusAggregator.java

@@ -27,6 +27,7 @@ import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.health.contributor.Status;
+import org.springframework.lang.Contract;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.ObjectUtils;
 
@@ -86,6 +87,7 @@ public class SimpleStatusAggregator implements StatusAggregator {
 		return codes.map(SimpleStatusAggregator::getUniformCode).toList();
 	}
 
+	@Contract("!null -> !null")
 	private static @Nullable String getUniformCode(@Nullable String code) {
 		if (code == null) {
 			return null;

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/info/InfoPropertiesInfoContributor.java

@@ -25,9 +25,11 @@ import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.context.properties.bind.Bindable;
 import org.springframework.boot.context.properties.bind.Binder;
+import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
 import org.springframework.boot.info.InfoProperties;
 import org.springframework.core.env.PropertySource;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -92,8 +94,16 @@ public abstract class InfoPropertiesInfoContributor<T extends InfoProperties> im
 	 * @return the raw content
 	 */
 	protected Map<String, Object> extractContent(PropertySource<?> propertySource) {
-		return new Binder(ConfigurationPropertySources.from(propertySource)).bind("", STRING_OBJECT_MAP)
-			.orElseGet(LinkedHashMap::new);
+		Iterable<@Nullable ConfigurationPropertySource> adapted = ConfigurationPropertySources.from(propertySource);
+		return new Binder(ensureNonNullContent(adapted)).bind("", STRING_OBJECT_MAP).orElseGet(LinkedHashMap::new);
+	}
+
+	private Iterable<ConfigurationPropertySource> ensureNonNullContent(
+			Iterable<@Nullable ConfigurationPropertySource> adapted) {
+		for (ConfigurationPropertySource source : adapted) {
+			Assert.state(source != null, "'source' must not be null");
+		}
+		return (Iterable<ConfigurationPropertySource>) adapted;
 	}
 
 	/**

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/security/AuthenticationAuditListener.java

@@ -89,7 +89,7 @@ public class AuthenticationAuditListener extends AbstractAuthenticationAuditList
 	}
 
 	private void onAuthenticationFailureEvent(AbstractAuthenticationFailureEvent event) {
-		Map<String, Object> data = new LinkedHashMap<>();
+		Map<String, @Nullable Object> data = new LinkedHashMap<>();
 		data.put("type", event.getException().getClass().getName());
 		data.put("message", event.getException().getMessage());
 		if (event.getAuthentication().getDetails() != null) {
@@ -99,7 +99,7 @@ public class AuthenticationAuditListener extends AbstractAuthenticationAuditList
 	}
 
 	private void onAuthenticationSuccessEvent(AuthenticationSuccessEvent event) {
-		Map<String, Object> data = new LinkedHashMap<>();
+		Map<String, @Nullable Object> data = new LinkedHashMap<>();
 		if (event.getAuthentication().getDetails() != null) {
 			data.put("details", event.getAuthentication().getDetails());
 		}
@@ -107,7 +107,7 @@ public class AuthenticationAuditListener extends AbstractAuthenticationAuditList
 	}
 
 	private void onLogoutSuccessEvent(LogoutSuccessEvent event) {
-		Map<String, Object> data = new LinkedHashMap<>();
+		Map<String, @Nullable Object> data = new LinkedHashMap<>();
 		if (event.getAuthentication().getDetails() != null) {
 			data.put("details", event.getAuthentication().getDetails());
 		}
@@ -119,7 +119,7 @@ public class AuthenticationAuditListener extends AbstractAuthenticationAuditList
 		void process(@Nullable AuthenticationAuditListener listener, AbstractAuthenticationEvent input) {
 			if (listener != null) {
 				AuthenticationSwitchUserEvent event = (AuthenticationSwitchUserEvent) input;
-				Map<String, Object> data = new HashMap<>();
+				Map<String, @Nullable Object> data = new HashMap<>();
 				if (event.getAuthentication().getDetails() != null) {
 					data.put("details", event.getAuthentication().getDetails());
 				}

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/security/AuthorizationAuditListener.java

@@ -50,7 +50,7 @@ public class AuthorizationAuditListener extends AbstractAuthorizationAuditListen
 
 	private void onAuthorizationDeniedEvent(AuthorizationDeniedEvent<?> event) {
 		String name = getName(event.getAuthentication());
-		Map<String, Object> data = new LinkedHashMap<>();
+		Map<String, @Nullable Object> data = new LinkedHashMap<>();
 		Object details = getDetails(event.getAuthentication());
 		if (details != null) {
 			data.put("details", details);

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/ssl/SslHealthIndicator.java

@@ -105,7 +105,9 @@ public class SslHealthIndicator extends AbstractHealthIndicator {
 	}
 
 	private boolean isExpiringCertificate(CertificateInfo certificate) {
-		return Instant.now().plus(this.expiryThreshold).isAfter(certificate.getValidityEnds());
+		Instant validityEnds = certificate.getValidityEnds();
+		Assert.state(validityEnds != null, "'validityEnds' must not be null");
+		return Instant.now().plus(this.expiryThreshold).isAfter(validityEnds);
 	}
 
 }

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/web/mappings/MappingsEndpoint.java

@@ -48,7 +48,7 @@ public class MappingsEndpoint {
 	@ReadOperation
 	public ApplicationMappingsDescriptor mappings() {
 		ApplicationContext target = this.context;
-		Map<String, ContextMappingsDescriptor> contextMappings = new HashMap<>();
+		Map<@Nullable String, ContextMappingsDescriptor> contextMappings = new HashMap<>();
 		while (target != null) {
 			contextMappings.put(target.getId(), mappingsForContext(target));
 			target = target.getParent();
@@ -69,13 +69,13 @@ public class MappingsEndpoint {
 	 */
 	public static final class ApplicationMappingsDescriptor implements OperationResponseBody {
 
-		private final Map<String, ContextMappingsDescriptor> contextMappings;
+		private final Map<@Nullable String, ContextMappingsDescriptor> contextMappings;
 
-		private ApplicationMappingsDescriptor(Map<String, ContextMappingsDescriptor> contextMappings) {
+		private ApplicationMappingsDescriptor(Map<@Nullable String, ContextMappingsDescriptor> contextMappings) {
 			this.contextMappings = contextMappings;
 		}
 
-		public Map<String, ContextMappingsDescriptor> getContexts() {
+		public Map<@Nullable String, ContextMappingsDescriptor> getContexts() {
 			return this.contextMappings;
 		}