code: public static String determineCollectionFromId(final String id) {
  		final int delimiter = id.indexOf(KEY_DELIMITER);
  		return delimiter == -1 ? null : id.substring(0, delimiter);
  	}
docs: Provides a substring with collection name.
  
  @param id
  string consisting of concatenation of collection name, /, & _key.
  @return collection name (or null if no key delimiter is present)