Nullability fine-tuning and related polishing

Issue: SPR-17250

spring-web/src/main/java/org/springframework/http/ReadOnlyHttpHeaders.java

@@ -31,7 +31,7 @@ import org.springframework.util.MultiValueMap;
  * {@code HttpHeaders} object that can only be read, not written to.
  *
  * @author Brian Clozel
- * @since 5.1
+ * @since 5.1.1
  */
 class ReadOnlyHttpHeaders extends HttpHeaders {
 
@@ -59,10 +59,7 @@ class ReadOnlyHttpHeaders extends HttpHeaders {
 	@Override
 	public List<String> get(Object key) {
 		List<String> values = this.headers.get(key);
-		if (values != null) {
-			return Collections.unmodifiableList(values);
-		}
-		return values;
+		return (values != null ? Collections.unmodifiableList(values) : null);
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/http/server/reactive/JettyHeadersAdapter.java

@@ -36,16 +36,18 @@ import org.springframework.util.MultiValueMap;
  * {@code MultiValueMap} implementation for wrapping Jetty HTTP headers.
  *
  * @author Brian Clozel
- * @since 5.1
+ * @since 5.1.1
  */
 class JettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	private final HttpFields headers;
 
+
 	JettyHeadersAdapter(HttpFields headers) {
 		this.headers = headers;
 	}
 
+
 	@Override
 	public String getFirst(String key) {
 		return this.headers.get(key);
@@ -95,24 +97,18 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public boolean isEmpty() {
-		return this.headers.size() == 0;
+		return (this.headers.size() == 0);
 	}
 
 	@Override
 	public boolean containsKey(Object key) {
-		if (key instanceof String) {
-			return this.headers.containsKey((String) key);
-		}
-		return false;
+		return (key instanceof String && this.headers.containsKey((String) key));
 	}
 
 	@Override
 	public boolean containsValue(Object value) {
-		if (value instanceof String) {
-			return this.headers.stream()
-					.anyMatch(field -> field.contains((String) value));
-		}
-		return false;
+		return (value instanceof String &&
+				this.headers.stream().anyMatch(field -> field.contains((String) value)));
 	}
 
 	@Nullable
@@ -144,8 +140,8 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 	}
 
 	@Override
-	public void putAll(Map<? extends String, ? extends List<String>> m) {
-		m.forEach(this::put);
+	public void putAll(Map<? extends String, ? extends List<String>> map) {
+		map.forEach(this::put);
 	}
 
 	@Override
@@ -179,6 +175,7 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 		};
 	}
 
+
 	private class EntryIterator implements Iterator<Entry<String, List<String>>> {
 
 		private Enumeration<String> names = headers.getFieldNames();
@@ -194,6 +191,7 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 		}
 	}
 
+
 	private class HeaderEntry implements Entry<String, List<String>> {
 
 		private final String key;
@@ -204,7 +202,7 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 
 		@Override
 		public String getKey() {
-			return this.key.toString();
+			return this.key;
 		}
 
 		@Override
@@ -219,4 +217,5 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 			return previousValues;
 		}
 	}
+
 }

spring-web/src/main/java/org/springframework/http/server/reactive/JettyHttpHandlerAdapter.java

@@ -34,12 +34,14 @@ import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
+import org.springframework.util.Assert;
 
 /**
  * {@link ServletHttpHandlerAdapter} extension that uses Jetty APIs for writing
  * to the response with {@link ByteBuffer}.
  *
  * @author Violeta Georgieva
+ * @author Brian Clozel
  * @since 5.0
  * @see org.springframework.web.server.adapter.AbstractReactiveWebInitializer
  */
@@ -53,6 +55,8 @@ public class JettyHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 	@Override
 	protected ServletServerHttpRequest createRequest(HttpServletRequest request, AsyncContext context)
 			throws IOException, URISyntaxException {
+
+		Assert.notNull(getServletPath(), "Servlet path is not initialized");
 		return new JettyServerHttpRequest(request, context, getServletPath(), getDataBufferFactory(), getBufferSize());
 	}
 
@@ -64,6 +68,7 @@ public class JettyHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 				response, context, getDataBufferFactory(), getBufferSize(), request);
 	}
 
+
 	private static final class JettyServerHttpRequest extends ServletServerHttpRequest {
 
 		JettyServerHttpRequest(HttpServletRequest request, AsyncContext asyncContext,

spring-web/src/main/java/org/springframework/http/server/reactive/NettyHeadersAdapter.java

@@ -34,16 +34,18 @@ import org.springframework.util.MultiValueMap;
  * {@code MultiValueMap} implementation for wrapping Netty HTTP headers.
  *
  * @author Brian Clozel
- * @since 5.1
+ * @since 5.1.1
  */
 class NettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	private final HttpHeaders headers;
 
+
 	NettyHeadersAdapter(HttpHeaders headers) {
 		this.headers = headers;
 	}
 
+
 	@Override
 	@Nullable
 	public String getFirst(String key) {
@@ -99,14 +101,14 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public boolean containsKey(Object key) {
-		return (key instanceof String) && this.headers.contains((String) key);
+		return (key instanceof String && this.headers.contains((String) key));
 	}
 
 	@Override
 	public boolean containsValue(Object value) {
-		return (value instanceof String) &&
+		return (value instanceof String &&
 				this.headers.entries().stream()
-						.anyMatch(entry -> value != null && value.equals(entry.getValue()));
+						.anyMatch(entry -> value.equals(entry.getValue())));
 	}
 
 	@Override
@@ -138,8 +140,8 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 	}
 
 	@Override
-	public void putAll(Map<? extends String, ? extends List<String>> m) {
-		m.forEach(this.headers::add);
+	public void putAll(Map<? extends String, ? extends List<String>> map) {
+		map.forEach(this.headers::add);
 	}
 
 	@Override
@@ -173,6 +175,7 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 		};
 	}
 
+
 	private class EntryIterator implements Iterator<Entry<String, List<String>>> {
 
 		private Iterator<String> names = headers.names().iterator();
@@ -188,6 +191,7 @@ class NettyHeadersAdapter implements MultiValueMap<String, String> {
 		}
 	}
 
+
 	private class HeaderEntry implements Entry<String, List<String>> {
 
 		private final String key;

spring-web/src/main/java/org/springframework/http/server/reactive/TomcatHeadersAdapter.java

@@ -38,23 +38,25 @@ import org.springframework.util.MultiValueMap;
  * {@code MultiValueMap} implementation for wrapping Tomcat HTTP headers.
  *
  * @author Brian Clozel
- * @since 5.1
+ * @since 5.1.1
  */
 class TomcatHeadersAdapter implements MultiValueMap<String, String> {
 
 	private final MimeHeaders headers;
 
+
 	TomcatHeadersAdapter(MimeHeaders headers) {
 		this.headers = headers;
 	}
 
+
 	@Override
 	public String getFirst(String key) {
 		return this.headers.getHeader(key);
 	}
 
 	@Override
-	public void add(String key, String value) {
+	public void add(String key, @Nullable String value) {
 		this.headers.addValue(key).setString(value);
 	}
 
@@ -69,7 +71,7 @@ class TomcatHeadersAdapter implements MultiValueMap<String, String> {
 	}
 
 	@Override
-	public void set(String key, String value) {
+	public void set(String key, @Nullable String value) {
 		this.headers.setValue(key).setString(value);
 	}
 
@@ -98,13 +100,13 @@ class TomcatHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public boolean isEmpty() {
-		return this.headers.size() == 0;
+		return (this.headers.size() == 0);
 	}
 
 	@Override
 	public boolean containsKey(Object key) {
 		if (key instanceof String) {
-			return this.headers.findHeader((String) key, 0) != -1;
+			return (this.headers.findHeader((String) key, 0) != -1);
 		}
 		return false;
 	}
@@ -152,8 +154,8 @@ class TomcatHeadersAdapter implements MultiValueMap<String, String> {
 	}
 
 	@Override
-	public void putAll(Map<? extends String, ? extends List<String>> m) {
-		m.forEach(this::put);
+	public void putAll(Map<? extends String, ? extends List<String>> map) {
+		map.forEach(this::put);
 	}
 
 	@Override
@@ -191,6 +193,7 @@ class TomcatHeadersAdapter implements MultiValueMap<String, String> {
 		};
 	}
 
+
 	private class EntryIterator implements Iterator<Entry<String, List<String>>> {
 
 		private Enumeration<String> names = headers.names();
@@ -206,11 +209,12 @@ class TomcatHeadersAdapter implements MultiValueMap<String, String> {
 		}
 	}
 
+
 	private final class HeaderEntry implements Entry<String, List<String>> {
 
 		private final String key;
 
-		private HeaderEntry(String key) {
+		HeaderEntry(String key) {
 			this.key = key;
 		}
 
@@ -234,4 +238,5 @@ class TomcatHeadersAdapter implements MultiValueMap<String, String> {
 			return previous;
 		}
 	}
+
 }

spring-web/src/main/java/org/springframework/http/server/reactive/TomcatHttpHandlerAdapter.java

@@ -48,7 +48,6 @@ import org.springframework.util.ReflectionUtils;
  *
  * @author Violeta Georgieva
  * @author Brian Clozel
- * @author Brian Clozel
  * @since 5.0
  * @see org.springframework.web.server.adapter.AbstractReactiveWebInitializer
  */
@@ -64,7 +63,7 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 	protected ServletServerHttpRequest createRequest(HttpServletRequest request, AsyncContext asyncContext)
 			throws IOException, URISyntaxException {
 
-		Assert.notNull(getServletPath(), "servletPath is not initialized.");
+		Assert.notNull(getServletPath(), "Servlet path is not initialized");
 		return new TomcatServerHttpRequest(
 				request, asyncContext, getServletPath(), getDataBufferFactory(), getBufferSize());
 	}
@@ -77,16 +76,20 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 				response, asyncContext, getDataBufferFactory(), getBufferSize(), request);
 	}
 
+
 	private static final class TomcatServerHttpRequest extends ServletServerHttpRequest {
 
-		private static final Field COYOTE_REQUEST_FIELD = ReflectionUtils.findField(RequestFacade.class, "request");
+		private static final Field COYOTE_REQUEST_FIELD;
 
 		private final int bufferSize;
 
 		private final DataBufferFactory factory;
 
 		static {
-			ReflectionUtils.makeAccessible(COYOTE_REQUEST_FIELD);
+			Field field = ReflectionUtils.findField(RequestFacade.class, "request");
+			Assert.state(field != null, "Incompatible Tomcat implementation");
+			ReflectionUtils.makeAccessible(field);
+			COYOTE_REQUEST_FIELD = field;
 		}
 
 		TomcatServerHttpRequest(HttpServletRequest request, AsyncContext context,
@@ -99,8 +102,10 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 		}
 
 		private static HttpHeaders createTomcatHttpHeaders(HttpServletRequest request) {
-			Request tomcatRequest = ((org.apache.catalina.connector.Request) ReflectionUtils
-					.getField(COYOTE_REQUEST_FIELD, request)).getCoyoteRequest();
+			org.apache.catalina.connector.Request connectorRequest = (org.apache.catalina.connector.Request)
+					ReflectionUtils.getField(COYOTE_REQUEST_FIELD, request);
+			Assert.state(connectorRequest != null, "No Tomcat connector request");
+			Request tomcatRequest = connectorRequest.getCoyoteRequest();
 			TomcatHeadersAdapter headers = new TomcatHeadersAdapter(tomcatRequest.getMimeHeaders());
 			return new HttpHeaders(headers);
 		}
@@ -112,11 +117,9 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 			DataBuffer dataBuffer = this.factory.allocateBuffer(capacity);
 			try {
 				ByteBuffer byteBuffer = dataBuffer.asByteBuffer(0, capacity);
-
 				ServletRequest request = getNativeRequest();
 				int read = ((CoyoteInputStream) request.getInputStream()).read(byteBuffer);
 				logBytesRead(read);
-
 				if (read > 0) {
 					dataBuffer.writePosition(read);
 					release = false;
@@ -140,10 +143,13 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 
 	private static final class TomcatServerHttpResponse extends ServletServerHttpResponse {
 
-		private static final Field COYOTE_RESPONSE_FIELD = ReflectionUtils.findField(ResponseFacade.class, "response");
+		private static final Field COYOTE_RESPONSE_FIELD;
 
 		static {
-			ReflectionUtils.makeAccessible(COYOTE_RESPONSE_FIELD);
+			Field field = ReflectionUtils.findField(ResponseFacade.class, "response");
+			Assert.state(field != null, "Incompatible Tomcat implementation");
+			ReflectionUtils.makeAccessible(field);
+			COYOTE_RESPONSE_FIELD = field;
 		}
 
 		TomcatServerHttpResponse(HttpServletResponse response, AsyncContext context,
@@ -153,8 +159,10 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 		}
 
 		private static HttpHeaders createTomcatHttpHeaders(HttpServletResponse response) {
-			Response tomcatResponse = ((org.apache.catalina.connector.Response) ReflectionUtils
-					.getField(COYOTE_RESPONSE_FIELD, response)).getCoyoteResponse();
+			org.apache.catalina.connector.Response connectorResponse = (org.apache.catalina.connector.Response)
+					ReflectionUtils.getField(COYOTE_RESPONSE_FIELD, response);
+			Assert.state(connectorResponse != null, "No Tomcat connector response");
+			Response tomcatResponse = connectorResponse.getCoyoteResponse();
 			TomcatHeadersAdapter headers = new TomcatHeadersAdapter(tomcatResponse.getMimeHeaders());
 			return new HttpHeaders(headers);
 		}

spring-web/src/main/java/org/springframework/http/server/reactive/UndertowHeadersAdapter.java

@@ -36,16 +36,18 @@ import org.springframework.util.MultiValueMap;
  * {@code MultiValueMap} implementation for wrapping Undertow HTTP headers.
  *
  * @author Brian Clozel
- * @since 5.1
+ * @since 5.1.1
  */
 class UndertowHeadersAdapter implements MultiValueMap<String, String> {
 
 	private final HeaderMap headers;
 
+
 	UndertowHeadersAdapter(HeaderMap headers) {
 		this.headers = headers;
 	}
 
+
 	@Override
 	public String getFirst(String key) {
 		return this.headers.getFirst(key);
@@ -92,25 +94,20 @@ class UndertowHeadersAdapter implements MultiValueMap<String, String> {
 
 	@Override
 	public boolean isEmpty() {
-		return this.headers.size() == 0;
+		return (this.headers.size() == 0);
 	}
 
 	@Override
 	public boolean containsKey(Object key) {
-		if (key instanceof String) {
-			return this.headers.contains((String) key);
-		}
-		return false;
+		return (key instanceof String && this.headers.contains((String) key));
 	}
 
 	@Override
 	public boolean containsValue(Object value) {
-		if (value instanceof String) {
-			return this.headers.getHeaderNames().stream()
-					.map(this.headers::get)
-					.anyMatch(values -> values.contains(value));
-		}
-		return false;
+		return (value instanceof String &&
+				this.headers.getHeaderNames().stream()
+						.map(this.headers::get)
+						.anyMatch(values -> values.contains(value)));
 	}
 
 	@Override
@@ -140,8 +137,8 @@ class UndertowHeadersAdapter implements MultiValueMap<String, String> {
 	}
 
 	@Override
-	public void putAll(Map<? extends String, ? extends List<String>> m) {
-		m.forEach((key, values) ->
+	public void putAll(Map<? extends String, ? extends List<String>> map) {
+		map.forEach((key, values) ->
 				this.headers.putAll(HttpString.tryFromString(key), values));
 	}
 
@@ -179,6 +176,7 @@ class UndertowHeadersAdapter implements MultiValueMap<String, String> {
 		};
 	}
 
+
 	private class EntryIterator implements Iterator<Entry<String, List<String>>> {
 
 		private Iterator<HttpString> names = headers.getHeaderNames().iterator();
@@ -194,6 +192,7 @@ class UndertowHeadersAdapter implements MultiValueMap<String, String> {
 		}
 	}
 
+
 	private class HeaderEntry implements Entry<String, List<String>> {
 
 		private final HttpString key;
@@ -219,4 +218,5 @@ class UndertowHeadersAdapter implements MultiValueMap<String, String> {
 			return previousValues;
 		}
 	}
+
 }