code: public final NumberExpression<Integer> size() {
          if (size == null) {
              size = Expressions.numberOperation(Integer.class, Ops.COL_SIZE, mixin);
          }
          return size;
      }
docs: Create a {@code this.size()} expression
  
  <p>Gets the number of elements in this collection</p>
  
  @return this.size()