Merge pull request #5691 from ctiller/idempotent

Makefile

include/grpc/grpc.h

include/grpc/impl/codegen/grpc_types.h

src/core/lib/channel/http_client_filter.c

src/core/lib/channel/http_server_filter.c

src/core/lib/surface/call.c

src/core/lib/surface/server.c

src/core/lib/transport/static_metadata.c

src/core/lib/transport/static_metadata.h

src/core/lib/transport/transport.h

src/cpp/server/server.cc

src/python/grpcio/grpc/_cython/imports.generated.h

src/ruby/ext/grpc/rb_grpc_imports.generated.h

test/core/bad_client/bad_client.c

test/core/end2end/end2end_nosec_tests.c

test/core/end2end/end2end_tests.c

test/core/end2end/fixtures/proxy.c

test/core/end2end/gen_build_yaml.py

test/core/end2end/tests/idempotent_request.c

test/core/end2end/tests/simple_request.c