question: public FlatBufferBuilder init ( ByteBuffer existing_bb ) { bb = existing_bb ; bb . clear ( ) ; bb . order ( ByteOrder . LITTLE_ENDIAN ) ; minalign = 1 ; space = bb . capacity ( ) ; vtable_in_use = 0 ; nested = false ; finished = false ; object_start = 0 ; num_vtables = 0 ; vector_num_elems = 0 ; return this ; }
target:  Alternative initializer that allows reusing this object on an existing `ByteBuffer`. This method resets the builder's internal state, but keeps objects that have been allocated for temporary storage.