Serialize vector of struct for flatbuffer in Java

Question

I am looking for an example of using vector of struct in flatbuffer in java. I tried looking at tutorial and https://github.com/google/flatbuffers/blob/master/samples/SampleBinary.java But so far have not found any good example. In tutorial https://google.github.io/flatbuffers/flatbuffers_guide_tutorial.html the code is

Monster.startPathVector(fbb, 2);
Vec3.createVec3(builder, 1.0f, 2.0f, 3.0f);
Vec3.createVec3(builder, 4.0f, 5.0f, 6.0f);
int path = fbb.endVector();

But it does not say when and how fbb is created. Any input would be appreciated. Thanks