docs: protected void writeMap(Map<?, ?> map, CharBuf buffer) {
          if (map.isEmpty()) {
              buffer.addChars(EMPTY_MAP_CHARS);
              return;
          }
          buffer.addChar(OPEN_BRACE);
          for (Map.Entry<?, ?> entry : map.entrySet()) {
              if (entry.getKey() == null) {
                  throw new IllegalArgumentException("Maps with null keys can\'t be converted to JSON");
              }
              String key = entry.getKey().toString();
              Object value = entry.getValue();
              if (isExcludingValues(value) || isExcludingFieldsNamed(key)) {
                  continue;
              }
              writeMapEntry(key, value, buffer);
              buffer.addChar(COMMA);
          }
          buffer.removeLastChar(COMMA); // dangling comma
          buffer.addChar(CLOSE_BRACE);
      }