code: private static InputMapping<Object> createInputMapping( Object value ){
          if( value instanceof String ){
              String text = (String)value;
              if( ElUtil.hasBrackets( text ) ){
                  return new ExpressionLanguageMapping<Object>( text );
              }
          }
          return ConstantMapping.of( value );
      }
docs: Creates an {@link InputMapping} based on a argument.
  @return {@link ExpressionLanguageMapping} for string arguments of style "${expression}",
  or a {@link ConstantMapping} otherwise.