Where's the memory leak?

ClosureWriter.java

public class ClosureWriter {

    protected interface UseExistingReference {}

    public void writeClosure(ClosureExpression expression) {
  	// create some byte-code
		// ...
		
		expression.setNodeMetaData(ClosureWriter.UseExistingReference.class,Boolean.TRUE);
		// do some more byte-code writing
		// ...
	}
}