Merge pull request #6798 from jboeuf/fix_3803

src/core/ext/transport/chttp2/transport/chttp2_transport.c

...ib/security/credentials/composite/composite_credentials.c

src/core/lib/security/credentials/credentials.c

src/core/lib/security/credentials/credentials.h

src/core/lib/security/credentials/fake/fake_credentials.c

src/core/lib/security/credentials/iam/iam_credentials.c

src/core/lib/security/credentials/jwt/jwt_credentials.c

...core/lib/security/credentials/oauth2/oauth2_credentials.c

...core/lib/security/credentials/plugin/plugin_credentials.c

src/core/lib/security/transport/client_auth_filter.c

test/core/security/credentials_test.c

test/core/security/oauth2_utils.c

test/core/security/print_google_default_creds_token.c

test/cpp/end2end/end2end_test.cc