code: protected static String determineCollectionName(Class<?> entityClass) {
      if (entityClass == null) {
          throw new InvalidJsonDbApiUsageException(
                "No class parameter provided, entity collection can't be determined");
      }
      Document doc = entityClass.getAnnotation(Document.class);
      if (null == doc) {
        throw new InvalidJsonDbApiUsageException(
            "Entity '" + entityClass.getSimpleName() + "' is not annotated with annotation @Document");
      }
      String collectionName = doc.collection();
  
      return collectionName;
    }
docs: A utility method to determine the collection name for a given entity class.
  This method attempts to find a the annotation {@link io.jsondb.annotation.Document} on this class.
  If found then we know the collection name else it throws a exception
  @param entityClass  class that determines the name of the collection
  @return  name of the class