code: protected String escape(String string) {
          if (!isEscape()) {
              return string;
          }
          if ((string == null) || (string.indexOf('\'') < 0)) {
              return string;
          }
          int n = string.length();
          StringBuffer sb = new StringBuffer(n);
          for (int i = 0; i < n; i++) {
              char ch = string.charAt(i);
              if (ch == '\'') {
                  sb.append('\'');
              }
              sb.append(ch);
          }
          return sb.toString();
      }
docs: ============