code: @Override
      protected void writeKey(Writer writer, FieldDescriptor key) throws IOException {
          writer.write(key.getClassDescriptor().getDottedClassName());
          writer.write(",");
          writer.write(key.getName());
          writer.write(",");
          writer.write(key.getSignature());
          writer.write(",");
          XField xField = XFactory.createXField(key);
          int flags = xField.getAccessFlags() & 0xf;
          writer.write(String.valueOf(flags));
      }
docs: /*
  (non-Javadoc)
  
  @see
  edu.umd.cs.findbugs.ba.interproc.PropertyDatabase#writeKey(java.io.Writer
  , KeyType)