Add validation query to DataSourceHealthIndicator details

See gh-15055

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/jdbc/DataSourceHealthIndicator.java

@@ -115,6 +115,7 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator
 					new SingleColumnRowMapper());
 			Object result = DataAccessUtils.requiredSingleResult(results);
 			builder.withDetail("result", result);
+			builder.withDetail("validationQuery", validationQuery);
 		}
 	}
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/jdbc/DataSourceHealthIndicatorTests.java

@@ -81,6 +81,8 @@ public class DataSourceHealthIndicatorTests {
 		assertThat(health.getDetails().get("database")).isNotNull();
 		assertThat(health.getStatus()).isEqualTo(Status.UP);
 		assertThat(health.getDetails().get("result")).isNotNull();
+		assertThat(health.getDetails().get("validationQuery"))
+				.isEqualTo("SELECT COUNT(*) from FOO");
 	}
 
 	@Test