code: public final Index getIndex( String indexName,
                                   String workspaceName ) {
          logger().trace("Looking for index '{0}' in '{1}' provider for query in workspace '{2}'", indexName, getName(),
                         workspaceName);
          Map<String, AtomicIndex> byWorkspaceNames = providedIndexesByWorkspaceNameByIndexName.get(indexName);
          return byWorkspaceNames == null ? null : byWorkspaceNames.get(workspaceName);
      }
docs: Get the queryable index with the given name and applicable for the given workspace.
  
  @param indexName the name of the index in this provider; never null
  @param workspaceName the name of the workspace; never null
  @return the queryable index, or null if there is no such index