code: public Chunk newChunk(String phrase, Span<Term> span) {
      String newId = idManager.getNextId(AnnotationType.CHUNK);
      Chunk newChunk = new Chunk(newId, span);
      newChunk.setPhrase(phrase);
      annotationContainer.add(newChunk, Layer.CHUNKS, AnnotationType.CHUNK);
      return newChunk;
  }
docs: Creates a new chunk. It assigns an appropriate ID to it. The Chunk is added to the document object.
  @param head the chunk head.
  @param phrase type of the phrase.
  @param terms the list of the terms in the chunk.
  @return a new chunk.