code: public String getDefaultWorkspaceName() {
          Document workspaces = doc.getDocument(FieldName.WORKSPACES);
          if (workspaces != null) {
              return workspaces.getString(FieldName.DEFAULT, Default.DEFAULT);
          }
          return Default.DEFAULT;
      }
docs: Get the name of the workspace that should be used for sessions where the client does not specify the name of the workspace.
  
  @return the default workspace name; never null