code: public boolean isTextContentType(String contentType) {
          if (contentType != null) {
              String lowerContentType = contentType.toLowerCase();
              for (String textContentType : this.parsableContentTypes) {
                  if (lowerContentType.startsWith(textContentType)) {
                      return true;
                  }
              }
          }
          return false;
      }
docs: Check whether the given content-type corresponds to "parseable" text.
  
  @param contentType
  the input content-type
  @return true if this represents text or false if not