code: package input;
  
  class Test_parameterized_type {
  	
  	@Override
  	public void processThis(Node externs, Node root) {
  		NodeTraversal.traverse(compiler, Preconditions.checkNotNull(this), this);
  	}
  	@Override
  	public void processNode(Node externs, Node root) {
  		NodeTraversal.traverse(compiler, Preconditions.checkNotNull(root), this);
  	}
  
  	class Preconditions {
  		@CanIgnoreReturnValue
  		public static <T> T checkNotNull(T reference) {
  			if (reference == null) {
  				throw new NullPointerException();
  			}
  			return reference;
  		}
  	}
  }