Update flatbuffers to 1.9.0 (tensorflow#20186)

* Update flatbuffers to 1.9.0

This fix updates flatbuffers to 1.9.0. The previous version
used (971a681) in tf was released last year, and is not
a versioned release. This fix updates to the latest versioned
release of 1.9.0.

Signed-off-by: Yong Tang <[email protected]>

* Add missing files of java_generator.cc to fix build error.

Signed-off-by: Yong Tang <[email protected]>

Author: yongtang

tensorflow/workspace.bzl

@@ -695,11 +695,11 @@ def tf_workspace(path_prefix="", tf_repo_name=""):
 
   tf_http_archive(
       name = "flatbuffers",
-      strip_prefix = "flatbuffers-971a68110e4fc1bace10fcb6deeb189e7e1a34ce",
-      sha256 = "874088d2ee0d9f8524191f77209556415f03dd44e156276edf19e5b90ceb5f55",
+      strip_prefix = "flatbuffers-1.9.0",
+      sha256 = "5ca5491e4260cacae30f1a5786d109230db3f3a6e5a0eb45d0d0608293d247e3",
       urls = [
-          "https://mirror.bazel.build/github.com/google/flatbuffers/archive/971a68110e4fc1bace10fcb6deeb189e7e1a34ce.tar.gz",
-          "https://github.com/google/flatbuffers/archive/971a68110e4fc1bace10fcb6deeb189e7e1a34ce.tar.gz",
+          "https://mirror.bazel.build/github.com/google/flatbuffers/archive/v1.9.0.tar.gz",
+          "https://github.com/google/flatbuffers/archive/v1.9.0.tar.gz",
       ],
       build_file = clean_dep("//third_party/flatbuffers:flatbuffers.BUILD"),
   )

third_party/flatbuffers/flatbuffers.BUILD

@@ -98,6 +98,8 @@ cc_binary(
         "grpc/src/compiler/cpp_generator.h",
         "grpc/src/compiler/go_generator.cc",
         "grpc/src/compiler/go_generator.h",
+        "grpc/src/compiler/java_generator.cc",
+        "grpc/src/compiler/java_generator.h",
         "grpc/src/compiler/schema_interface.h",
         "src/flatc_main.cpp",
         "src/idl_gen_cpp.cpp",