code: public static ModuleIdentifier asModuleIdentifier(ModelNode value, ModuleIdentifier defaultValue) {
          return value.isDefined() ? ModuleIdentifier.fromString(value.asString()) : defaultValue;
      }
docs: Returns the value of the node as a module identifier, or the specified default if the node is undefined.
  @param value a model node
  @return the value of the node as a module identifier, or the specified default if the node is undefined.