/** For failed actions, more information on the cause of the failure. */
 @NotNull
 public Builder error(@NotNull Thing.Builder thing) {
   putValue("error", thing.build());
   return this;
 }
 /**
  * Indicates that the CreativeWork contains a reference to, but is not necessarily about a
  * concept.
  */
 @NotNull
 public Builder mentions(@NotNull Thing.Builder thing) {
   putValue("mentions", thing.build());
   return this;
 }
 /** The subject matter of the content. */
 @NotNull
 public Builder about(@NotNull Thing.Builder thing) {
   putValue("about", thing.build());
   return this;
 }
 /** Indicates the primary entity described in some page or other CreativeWork. */
 @NotNull
 public Builder mainEntity(@NotNull Thing.Builder thing) {
   putValue("mainEntity", thing.build());
   return this;
 }
 /** A goal towards an action is taken. Can be concrete or abstract. */
 @NotNull
 public Builder purpose(@NotNull Thing.Builder thing) {
   putValue("purpose", thing.build());
   return this;
 }