private RpcResponse handleException(ServiceRequestContext ctx, Throwable cause) {
        final RpcResponse res = exceptionHandler.apply(ctx, cause);
        if (res == null) {
            logger.warn("exceptionHandler.apply() returned null.");
            return RpcResponse.ofFailure(cause);
        }
        return res;
    }
Returns the default {@link SerializationFormat} of this service.
thrift/thrift0.13/src/main/java/com/linecorp/armeria/server/thrift/THttpService.java