in src/main/java/org/apache/datasketches/memory/internal/ResourceImpl.java [508:514]
public final long nativeOverlap(final Resource that) {
if (that == null) { return 0; }
if (!that.isAlive()) { return 0; }
final ResourceImpl that2 = (ResourceImpl) that;
if (this == that2) { return seg.byteSize(); }
return nativeOverlap(seg, that2.seg);
}