fix for feature2d java wrappers as described in this post: http://ans… (#7372)

* fix for feature2d java wrappers as described in this post: http://answers.opencv.org/question/101675/surfsift-java-wrapper-for-opencv-3xosx-1011/

* fix for feature2d java wrappers as described in this post: http://answers.opencv.org/question/101675/surfsift-java-wrapper-for-opencv-3xosx-1011/

* rollback of one change as requested (similar change already merged)

modules/java/generator/gen_java.py

@@ -807,6 +807,8 @@ class ClassInfo(GeneralInfo):
             self.imports.add("java.util.List")
             self.imports.add("java.util.ArrayList")
             self.addImports(ctype.replace('vector_vector', 'vector'))
+        elif ctype.startswith('Feature2D'):
+            self.imports.add("org.opencv.features2d.Feature2D")
         elif ctype.startswith('vector'):
             self.imports.add("org.opencv.core.Mat")
             self.imports.add('java.util.ArrayList')