@Override
    public String serializeExampleRequest(String serviceName, String methodName,
                                          Object exampleRequest) {
        try {
            return defaultExamplePrinter.print((MessageOrBuilder) exampleRequest);
        } catch (InvalidProtocolBufferException e) {
            throw new UncheckedIOException(
                    "Invalid example request protobuf. Is it missing required fields?", e);
        }
    }
{@link DocServicePlugin} implementation that supports {@link GrpcService}s.
grpc/src/main/java/com/linecorp/armeria/internal/server/grpc/GrpcDocServicePlugin.java