code: private Map<String, Object> buildHierarchyParameters(final List<String> parents, final List<String> children) {
          final MultiMap<String, Object> parameters = new MultiMap<>();
  
          if (parents != null) {
              for (final String parent : parents) {
                  parameters.put("parents", parent);
              }
          }
  
          if (children != null) {
              for (final String child : children) {
                  parameters.put("children", child);
              }
          }
  
          return parameters;
      }
docs: Build the hierarchy parameters map for a create group request