[java] provide apis to access nested vectors and buffers

[asfimport]

To facilitate vectorized writes to vector we'd wand to provide access to underlying nested vectors and buffers.

Reporter: Julien Le Dem / @julienledem
Assignee: Julien Le Dem / @julienledem

Related issues:

• Arrow release 0.2 (blocks)

PRs and other links:

• PR

_{Note: This issue was originally created as ARROW-524. Please see the migration documentation for further details.}

[asfimport]

Julien Le Dem / @julienledem:
PR: #314

[asfimport]

Uwe Korn / @xhochy:
Issue resolved by pull request 314
#314