essage (has_XXX works for message fields).
We don't use google/protobuf/wrappers.proto because depending on it makes
the following android integration test fail:
<a href="http://sponge/c4bce1fd-41bd-4d0b-b4ca-fc04d4d64621">http://sponge/c4bce1fd-41bd-4d0b-b4ca-fc04d4d64621</a>
</pre><p>Protobuf type</p><div class="fragment"><div class="line">operations_research.OptionalDouble </div>
</div><!-- fragment --> 
<p class="definition">Definition at line <a class="el" href="OptionalDouble_8java_source.html#l00290"