code: protected static FileSizeFilter create(RelationalOperator<Long> operator) {
      return new FileSizeFilter() {
        @Override @NullSafe
        public boolean accept(File file) {
          return (file != null && operator.evaluate(file.length()));
        }
      };
    }
docs: Factory method to create an instance of the {@link FileSizeFilter} initialized with the given
  {@link RelationalOperator} used during the filtering process to evaluate {@link File}s by size.
  
  @param operator [{@link RelationalOperator} used to evaluate a {@link File}'s size.
  @return an instance of {@link FileSizeFilter}.
  @see org.cp.elements.lang.RelationalOperator#evaluate(Comparable)
  @see org.cp.elements.io.FileSizeFilter
  @see java.io.File