[Feat][Java] Make iter support foreach loop

[Thespica]

Is your feature request related to a problem? Please describe.
Now, there are some iters of collection, but must been used like for (EdgeIter it = edges2.begin(); !it.eq(end2); it.inc())
Describe the solution you'd like
Implement java.lang.Iterable interface with default method.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.