Print the java version being used on startup

See gh-21559

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/StartupInfoLogger.java

@@ -67,6 +67,7 @@ class StartupInfoLogger {
 		message.append("Starting ");
 		appendApplicationName(message);
 		appendVersion(message, this.sourceClass);
+		appendJavaVersion(message);
 		appendOn(message);
 		appendPid(message);
 		appendContext(message);
@@ -147,6 +148,10 @@ class StartupInfoLogger {
 		}
 	}
 
+	private void appendJavaVersion(StringBuilder message) {
+		append(message, "using Java ", () -> System.getProperty("java.version"));
+	}
+
 	private void append(StringBuilder message, String prefix, Callable<Object> call) {
 		append(message, prefix, call, "");
 	}