Method getHeaderValue

xds/src/main/java/io/grpc/xds/RoutingUtils.java:174–190

(Metadata headers, String headerName)

  }

  @Nullable
  private static String getHeaderValue(Metadata headers, String headerName) {
    if (headerName.endsWith(Metadata.BINARY_HEADER_SUFFIX)) {
      return null;
    }
    if (headerName.equals("content-type")) {
      return "application/grpc";
    }
    Metadata.Key<String> key;
    try {
      key = Metadata.Key.of(headerName, Metadata.ASCII_STRING_MARSHALLER);
    } catch (IllegalArgumentException e) {
      return null;
    }
    Iterable<String> values = headers.getAll(key);
    return values == null ? null : Joiner.on(",").join(values);
  }
}