Improve error message for non-options-capable ConnectionFactory

Fixes gh-26977

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/r2dbc/EmbeddedDatabaseConnection.java

@@ -101,7 +101,9 @@ public enum EmbeddedDatabaseConnection {
 		OptionsCapableConnectionFactory optionsCapable = OptionsCapableConnectionFactory.unwrapFrom(connectionFactory);
 		if (optionsCapable == null) {
 			throw new IllegalArgumentException(
-					"Cannot determine database's type as ConnectionFactory is not options-capable");
+					"Cannot determine database's type as ConnectionFactory is not options-capable. To be "
+							+ "options-capable, a ConnectionFactory should be created with "
+							+ ConnectionFactoryBuilder.class.getName());
 		}
 		ConnectionFactoryOptions options = optionsCapable.getOptions();
 		for (EmbeddedDatabaseConnection candidate : values()) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/r2dbc/EmbeddedDatabaseConnectionTests.java

@@ -89,7 +89,9 @@ class EmbeddedDatabaseConnectionTests {
 		assertThatIllegalArgumentException()
 				.isThrownBy(() -> EmbeddedDatabaseConnection
 						.isEmbedded(ConnectionFactories.get("r2dbc:pool:h2:mem:///" + UUID.randomUUID())))
-				.withMessage("Cannot determine database's type as ConnectionFactory is not options-capable");
+				.withMessage("Cannot determine database's type as ConnectionFactory is not options-capable. To be "
+						+ "options-capable, a ConnectionFactory should be created with "
+						+ "org.springframework.boot.r2dbc.ConnectionFactoryBuilder");
 	}
 
 	static Stream<Arguments> urlParameters() {