code: public void mergeMapSection(int line, int column, String mapSectionContents)
        throws SourceMapParseException {
      setStartingPosition(line, column);
      SourceMapConsumerV3 section = new SourceMapConsumerV3();
      section.parse(mapSectionContents);
      section.visitMappings(new ConsumerEntryVisitor());
    }
docs: Merges current mapping with {@code mapSectionContents} considering the
  offset {@code (line, column)}. Any extension in the map section will be
  ignored.
  
  @param line The line offset
  @param column The column offset
  @param mapSectionContents The map section to be appended
  @throws SourceMapParseException