code: private static String getCollectionName(BackendQuery<?> customQuery, MongoDBQueryDescriptor queryDescriptor, EntityKeyMetadata entityKeyMetadata) {
  		if ( queryDescriptor.getCollectionName() != null ) {
  			return queryDescriptor.getCollectionName();
  		}
  		else if ( entityKeyMetadata != null ) {
  			return entityKeyMetadata.getTable();
  		}
  		else {
  			throw log.unableToDetermineCollectionName( customQuery.getQuery().toString() );
  		}
  	}
docs: Returns the name of the MongoDB collection to execute the given query against. Will either be retrieved
  <ul>
  <li>from the given query descriptor (in case the query has been translated from JP-QL or it is a native query
  using the extended syntax {@code db.<COLLECTION>.<OPERATION>(...)}</li>
  <li>or from the single mapped entity type if it is a native query using the criteria-only syntax
  
  @param customQuery the original query to execute
  @param queryDescriptor descriptor for the query
  @param entityKeyMetadata meta-data in case this is a query with exactly one entity return
  @return the name of the MongoDB collection to execute the given query against