fix encrypted String size()
fix encrypted String size()

kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers,kiyoto-suzuki/flatbuffers