Add support for deriving a DataSourceBuilder from a wrapped DataSource

Closes gh-31605

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/jdbc/DataSourceBuilder.java

@@ -236,7 +236,35 @@ public final class DataSourceBuilder<T extends DataSource> {
 				throw new IllegalStateException("Unable to unwrap embedded database", ex);
 			}
 		}
-		return new DataSourceBuilder<>(dataSource);
+		try {
+			while (dataSource.isWrapperFor(DataSource.class)) {
+				DataSource unwrapped = dataSource.unwrap(DataSource.class);
+				if (unwrapped == dataSource) {
+					break;
+				}
+				dataSource = unwrapped;
+			}
+		}
+		catch (SQLException ex) {
+			// Try to continue with the existing, potentially still wrapped, DataSource
+		}
+		return new DataSourceBuilder<>(unwrap(dataSource));
+	}
+
+	private static DataSource unwrap(DataSource dataSource) {
+		try {
+			while (dataSource.isWrapperFor(DataSource.class)) {
+				DataSource unwrapped = dataSource.unwrap(DataSource.class);
+				if (unwrapped == dataSource) {
+					return unwrapped;
+				}
+				dataSource = unwrapped;
+			}
+		}
+		catch (SQLException ex) {
+			// Try to continue with the existing, potentially still wrapped, DataSource
+		}
+		return dataSource;
 	}
 
 	/**

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/jdbc/DataSourceBuilderTests.java

@@ -18,11 +18,14 @@ package org.springframework.boot.jdbc;
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.io.PrintWriter;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.sql.Connection;
 import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
 import java.util.Arrays;
+import java.util.logging.Logger;
 
 import javax.sql.DataSource;
 
@@ -343,6 +346,19 @@ class DataSourceBuilderTests {
 		assertThat(built.getUrl()).startsWith("jdbc:hsqldb:mem");
 	}
 
+	@Test
+	void buildWhenDerivedFromWrappedDataSource() {
+		HikariDataSource dataSource = new HikariDataSource();
+		dataSource.setUsername("test");
+		dataSource.setPassword("secret");
+		dataSource.setJdbcUrl("jdbc:h2:test");
+		DataSourceBuilder<?> builder = DataSourceBuilder.derivedFrom(wrap(wrap(dataSource)));
+		HikariDataSource built = (HikariDataSource) builder.username("test2").password("secret2").build();
+		assertThat(built.getUsername()).isEqualTo("test2");
+		assertThat(built.getPassword()).isEqualTo("secret2");
+		assertThat(built.getJdbcUrl()).isEqualTo("jdbc:h2:test");
+	}
+
 	@Test // gh-26644
 	void buildWhenDerivedFromExistingDatabaseWithTypeChange() {
 		HikariDataSource dataSource = new HikariDataSource();
@@ -384,6 +400,65 @@ class DataSourceBuilderTests {
 		assertThat(testSource.getPassword()).isEqualTo("secret");
 	}
 
+	private DataSource wrap(DataSource target) {
+		return new DataSourceWrapper(target);
+	}
+
+	private static final class DataSourceWrapper implements DataSource {
+
+		private final DataSource delegate;
+
+		private DataSourceWrapper(DataSource delegate) {
+			this.delegate = delegate;
+		}
+
+		@Override
+		public Logger getParentLogger() throws SQLFeatureNotSupportedException {
+			return this.delegate.getParentLogger();
+		}
+
+		@Override
+		public <T> T unwrap(Class<T> iface) throws SQLException {
+			return this.delegate.unwrap(iface);
+		}
+
+		@Override
+		public boolean isWrapperFor(Class<?> iface) throws SQLException {
+			return this.delegate.isWrapperFor(iface);
+		}
+
+		@Override
+		public Connection getConnection() throws SQLException {
+			return this.delegate.getConnection();
+		}
+
+		@Override
+		public Connection getConnection(String username, String password) throws SQLException {
+			return this.delegate.getConnection(username, password);
+		}
+
+		@Override
+		public PrintWriter getLogWriter() throws SQLException {
+			return this.delegate.getLogWriter();
+		}
+
+		@Override
+		public void setLogWriter(PrintWriter out) throws SQLException {
+			this.delegate.setLogWriter(out);
+		}
+
+		@Override
+		public void setLoginTimeout(int seconds) throws SQLException {
+			this.delegate.setLoginTimeout(seconds);
+		}
+
+		@Override
+		public int getLoginTimeout() throws SQLException {
+			return this.delegate.getLoginTimeout();
+		}
+
+	}
+
 	final class HidePackagesClassLoader extends URLClassLoader {
 
 		private final String[] hiddenPackages;