As discussed in https://github.com/apache/arrow/pull/121 for
ARROW-262, the Struct name is reserved in Flatbuffers, so we temporarily used the `Tuple` name. We should either use a tweaked name like Struct_ that does not cause conflicts or choose a name for the Struct concept (e.g. Tuple) and use that consistently in format documents and implementation.
The least disruptive solution is to use the Struct_ name in the Flatbuffers IDL.