Compilation error saying ...source level is at least 1.8 in GWT 2.7.0

Hi

When I compiled my Project, I encountered a problem saying that "Syntax error, type annotations are available only when source level is at least 1.8"

This error is coming for using @Nullable in source code in client side in my application.


import org.eclipse.jdt.annotation.Nullable;

valuesManager.saveData(new DSCallback() {
@Override
public void execute(@Nullable DSResponse response, Object rawData, DSRequest request) {

}
});

There is no problem when i build my application using same code.
Problems come when i am going to compile my application.

I have already set my project compilation level to 1.8. But this did not solve my problem.

In any situation I can not avoid this annotations in my source code.
I have to use this code as it is a client request.

My working environment is

java 1.8.0_40 (64 bit)
GWT 2.7.0
SmartClient Version: v8.3_2012-11-20/PowerEdition Deployment (built 2012-11-20)
STS Eclipse Luna SR1 (4.4.1)


Please advise.

Regards

DEV