public void setClassAnnotations(Annotations annotations, DexFile dexFile) {
    if (annotations == null) {
      throw new NullPointerException("annotations == null");
    }

    if (classAnnotations != null) {
      throw new UnsupportedOperationException("class annotations already set");
    }

    classAnnotations = new AnnotationSetItem(annotations, dexFile);
  }
Sets the direct annotations on this instance. These are annotations made on the class, per se,
as opposed to on one of its members. It is only valid to call this method at most once per
instance.

@param annotations {@code non-null;} annotations to set for this class
@param dexFile {@code non-null;} dex output
android/android_framework/dex-maker/src/main/java/com/android/dx/dex/file/AnnotationsDirectoryItem.java