opencv/modules/features/misc/java/gen_dict.json

{
    "type_dict" : {
        "Feature2D": {
            "j_type": "Feature2D",
            "jn_type": "long",
            "jni_type": "jlong",
            "jni_var": "Feature2D %(n)s",
            "suffix": "J",
            "j_import": "org.opencv.features.Feature2D"
        }
    }
}