Improve null-safety of module/spring-boot-r2dbc

See gh-46926

module/spring-boot-r2dbc/src/main/java/org/springframework/boot/r2dbc/autoconfigure/R2dbcAutoConfiguration.java

@@ -16,7 +16,6 @@
 
 package org.springframework.boot.r2dbc.autoconfigure;
 
-import java.util.function.Predicate;
 import java.util.function.Supplier;
 
 import io.r2dbc.spi.ConnectionFactory;
@@ -34,6 +33,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnResource;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -72,26 +72,43 @@ public final class R2dbcAutoConfiguration {
 
 		@Override
 		public ConnectionFactoryOptions getConnectionFactoryOptions() {
-			ConnectionFactoryOptions urlOptions = ConnectionFactoryOptions.parse(this.properties.getUrl());
+			String url = this.properties.getUrl();
+			Assert.state(url != null, "'url' must not be null");
+			ConnectionFactoryOptions urlOptions = ConnectionFactoryOptions.parse(url);
 			Builder optionsBuilder = urlOptions.mutate();
-			configureIf(optionsBuilder, urlOptions, ConnectionFactoryOptions.USER, this.properties::getUsername,
-					StringUtils::hasText);
-			configureIf(optionsBuilder, urlOptions, ConnectionFactoryOptions.PASSWORD, this.properties::getPassword,
-					StringUtils::hasText);
-			configureIf(optionsBuilder, urlOptions, ConnectionFactoryOptions.DATABASE,
-					() -> determineDatabaseName(this.properties), StringUtils::hasText);
+			configureUser(optionsBuilder, urlOptions);
+			configurePassword(optionsBuilder, urlOptions);
+			configureDatabase(optionsBuilder, urlOptions);
 			this.properties.getProperties().forEach((key, value) -> optionsBuilder.option(Option.valueOf(key), value));
 			return optionsBuilder.build();
 		}
 
+		// Lambda isn't detected with the correct nullability
+		@SuppressWarnings("NullAway")
+		private void configureDatabase(Builder optionsBuilder, ConnectionFactoryOptions urlOptions) {
+			configureIf(optionsBuilder, urlOptions, ConnectionFactoryOptions.DATABASE,
+					() -> determineDatabaseName(this.properties));
+		}
+
+		// Lambda isn't detected with the correct nullability
+		@SuppressWarnings("NullAway")
+		private void configurePassword(Builder optionsBuilder, ConnectionFactoryOptions urlOptions) {
+			configureIf(optionsBuilder, urlOptions, ConnectionFactoryOptions.PASSWORD, this.properties::getPassword);
+		}
+
+		// Lambda isn't detected with the correct nullability
+		@SuppressWarnings("NullAway")
+		private void configureUser(Builder optionsBuilder, ConnectionFactoryOptions urlOptions) {
+			configureIf(optionsBuilder, urlOptions, ConnectionFactoryOptions.USER, this.properties::getUsername);
+		}
+
 		private <T extends CharSequence> void configureIf(Builder optionsBuilder,
-				ConnectionFactoryOptions originalOptions, Option<T> option, Supplier<T> valueSupplier,
-				Predicate<T> setIf) {
+				ConnectionFactoryOptions originalOptions, Option<T> option, Supplier<@Nullable T> valueSupplier) {
 			if (originalOptions.hasOption(option)) {
 				return;
 			}
 			T value = valueSupplier.get();
-			if (setIf.test(value)) {
+			if (StringUtils.hasText(value)) {
 				optionsBuilder.option(option, value);
 			}
 		}

module/spring-boot-r2dbc/src/main/java/org/springframework/boot/r2dbc/docker/compose/ClickHouseEnvironment.java

@@ -37,9 +37,19 @@ class ClickHouseEnvironment {
 	private final String database;
 
 	ClickHouseEnvironment(Map<String, @Nullable String> env) {
-		this.username = env.getOrDefault("CLICKHOUSE_USER", "default");
+		this.username = extractUsername(env);
 		this.password = extractPassword(env);
-		this.database = env.getOrDefault("CLICKHOUSE_DB", "default");
+		this.database = extractDatabase(env);
+	}
+
+	private static String extractDatabase(Map<String, @Nullable String> env) {
+		String result = env.get("CLICKHOUSE_DB");
+		return (result != null) ? result : "default";
+	}
+
+	private static String extractUsername(Map<String, @Nullable String> env) {
+		String result = env.get("CLICKHOUSE_USER");
+		return (result != null) ? result : "default";
 	}
 
 	private String extractPassword(Map<String, @Nullable String> env) {

module/spring-boot-r2dbc/src/main/java/org/springframework/boot/r2dbc/docker/compose/MariaDbEnvironment.java

@@ -47,7 +47,10 @@ class MariaDbEnvironment {
 
 	private String extractUsername(Map<String, @Nullable String> env) {
 		String user = env.get("MARIADB_USER");
-		return (user != null) ? user : env.getOrDefault("MYSQL_USER", "root");
+		if (user == null) {
+			user = env.get("MYSQL_USER");
+		}
+		return (user != null) ? user : "root";
 	}
 
 	private String extractPassword(Map<String, @Nullable String> env) {

module/spring-boot-r2dbc/src/main/java/org/springframework/boot/r2dbc/docker/compose/MySqlEnvironment.java

@@ -40,11 +40,16 @@ class MySqlEnvironment {
 	private final String database;
 
 	MySqlEnvironment(Map<String, @Nullable String> env) {
-		this.username = env.getOrDefault("MYSQL_USER", "root");
+		this.username = extractUsername(env);
 		this.password = extractPassword(env);
 		this.database = extractDatabase(env);
 	}
 
+	private static String extractUsername(Map<String, @Nullable String> env) {
+		String result = env.get("MYSQL_USER");
+		return (result != null) ? result : "root";
+	}
+
 	private String extractPassword(Map<String, @Nullable String> env) {
 		Assert.state(!env.containsKey("MYSQL_RANDOM_ROOT_PASSWORD"), "MYSQL_RANDOM_ROOT_PASSWORD is not supported");
 		boolean allowEmpty = env.containsKey("MYSQL_ALLOW_EMPTY_PASSWORD") || env.containsKey("ALLOW_EMPTY_PASSWORD");

module/spring-boot-r2dbc/src/main/java/org/springframework/boot/r2dbc/docker/compose/OracleEnvironment.java

@@ -37,9 +37,19 @@ class OracleEnvironment {
 	private final String database;
 
 	OracleEnvironment(Map<String, @Nullable String> env, String defaultDatabase) {
-		this.username = env.getOrDefault("APP_USER", "system");
+		this.username = extractUsername(env);
 		this.password = extractPassword(env);
-		this.database = env.getOrDefault("ORACLE_DATABASE", defaultDatabase);
+		this.database = extractDatabase(env, defaultDatabase);
+	}
+
+	private static String extractDatabase(Map<String, @Nullable String> env, String defaultDatabase) {
+		String result = env.get("ORACLE_DATABASE");
+		return (result != null) ? result : defaultDatabase;
+	}
+
+	private static String extractUsername(Map<String, @Nullable String> env) {
+		String result = env.get("APP_USER");
+		return (result != null) ? result : "system";
 	}
 
 	private String extractPassword(Map<String, @Nullable String> env) {

module/spring-boot-r2dbc/src/main/java/org/springframework/boot/r2dbc/docker/compose/PostgresEnvironment.java

@@ -57,8 +57,9 @@ class PostgresEnvironment {
 
 	private String extract(Map<String, @Nullable String> env, String[] keys, String defaultValue) {
 		for (String key : keys) {
-			if (env.containsKey(key)) {
-				return env.get(key);
+			String value = env.get(key);
+			if (value != null) {
+				return value;
 			}
 		}
 		return defaultValue;