https://github.com/bytedeco/javacpp/wiki/Basic-Architecture#the-pointer
http://bytedeco.org/javacpp/apidocs/org/bytedeco/javacpp/Pointer.html
http://bytedeco.org/javacpp/apidocs/org/bytedeco/javacpp/PointerScope.html

https://github.com/bytedeco/javacpp/blob/master/src/main/java/org/bytedeco/javacpp/IntPointer.java
    // java
    public native void getInt(@ByPtr IntPointer i);
    // cpp
    void getInt(int *pI) { *pI = 7; }
    // test
    IntPointer iP = new IntPointer(1); // 1 element
    try {
        l.getInt(iP);
        assertThat(iP.get()).isEqualTo(7);
    } finally {
        if (iP != null) {
            iP.deallocate();
        }
    }

    // java
    public native int getArr(@ByRef @StdVector int [] elements);
    // cpp
    int
    getArr(std::vector<int> &elements)
    {
        elements[0] = 5;
        elements[1] = 7;
        return 2;
    }    
    // test
    int [] elements = new int[10000];

    int res = l.getArr(elements);
    assertThat(res).isEqualTo(2);

    assertThat(elements[0]).isEqualTo(5);
    assertThat(elements[1]).isEqualTo(7);