@Test public void testCustomHeaderKeys() { ApiClientHeaderProvider provider = ApiClientHeaderProvider.newBuilder() .setTransportToken("grpc", "1.2.3") .setGeneratedLibToken("gapic", "4.5.6") .setResourceToken("test-prefix") .setApiClientHeaderKey("custom-header1") .setResourceHeaderKey("custom-header2") .build(); assertThat(provider.getHeaders().size()).isEqualTo(2); assertThat(provider.getHeaders().get("custom-header1")) .matches("^gl-java/.* gapic/4\\.5\\.6 gax/.* grpc/1\\.2\\.3$"); assertThat(provider.getHeaders().get("custom-header2")).isEqualTo("test-prefix"); } }