code: public String stripExpression(String expression) {
          if (expression == null) {
              throw new IllegalArgumentException("Cannot strip NULL expression!");
          }
          expression = expression.replaceAll("^\\$\\{", "").replaceAll("\\}$", "");
          expression = expression.replaceAll("^#\\{", "").replaceAll("\\}$", "");
          return expression;
      }
docs: Strips an expression of the leading "${" or "#{" and the trailing "}".
  
  @param expression the expression to strip.
  @return the expression without the leading "${" or "#{" and the trailing "}".