title: JNI - native method with ByteBuffer parameter
body: <p>I've got a method:</p>
  
  <pre><code>public native void doSomething(ByteBuffer in, ByteBuffer out);
  </code></pre>
  
  <p>Generated by javah C/C++ header of this method is:</p>
  
  <pre><code>JNIEXPORT void JNICALL Java__MyClass_doSomething (JNIEnv *, jobject, jobject, jobject, jint, jint);
  </code></pre>
  
  <p>How can I get a data array from jobject (that is a ByteBuffer instance) ?</p>