code: private String[] getParameters(ELNode.Function func)
              throws JspTranslationException {
          FunctionInfo funcInfo = func.getFunctionInfo();
          String signature = funcInfo.getFunctionSignature();
          ArrayList params = new ArrayList();
          // Signature is of the form
          // <return-type> S <method-name S? '('
          // < <arg-type> ( ',' <arg-type> )* )? ')'
          int start = signature.indexOf('(') + 1;
          boolean lastArg = false;
          while (true) {
              int p = signature.indexOf(',', start);
              if (p < 0) {
                  p = signature.indexOf(')', start);
                  if (p < 0) {
  	                throw new JspTranslationException("jsp.error.tld.fn.invalid.signature " + func.getPrefix()+" "+ func.getName());					
                  }
                  lastArg = true;
              }
              String arg = signature.substring(start, p).trim();
              if (!"".equals(arg)) {
                  params.add(arg);
              }
              if (lastArg) {
                  break;
              }
              start = p + 1;
          }
          return (String[]) params.toArray(new String[params.size()]);
      }
docs: Get the parameters types from the function signature.
  
  @return An array of parameter class names