code: private String getMethod(ELNode.Function func) throws JspTranslationException {
          FunctionInfo funcInfo = func.getFunctionInfo();
          String signature = funcInfo.getFunctionSignature();
  
          int start = signature.indexOf(' ');
          if (start < 0) {
              throw new JspTranslationException("jsp.error.tld.fn.invalid.signature " + func.getPrefix()+" "+ func.getName());					
          }
          int end = signature.indexOf('(');
          if (end < 0) {
              throw new JspTranslationException("jsp.error.tld.fn.invalid.signature.parenexpected " + func.getPrefix()+" "+ func.getName());					
          }
          return signature.substring(start + 1, end).trim();
      }
docs: Get the method name from the signature.