code: public NumberExpression<T> negate() {
          if (negation == null) {
              negation = Expressions.numberOperation(getType(), Ops.NEGATE, mixin);
          }
          return negation;
      }
docs: Create a {@code this * -1} expression
  
  <p>Get the negation of this expression</p>
  
  @return this * -1