spring-cloud-feign 使用@RequetParam报错QueryMap parameter must be a Map: class java.lang.String

这里使用spring-cloud-start-feign: 1.2.2 REALEASE版本，依赖管理器版本是 Camden.SR2

出错的原因是@RequestParam的value为empty时，参数会被当作Map来处理

org.springframework.cloud.netflix.feign.annotation.RequestParamParameterProcessor

代码如下：

    @Override
	public boolean processArgument(AnnotatedParameterContext context,
			Annotation annotation) {
		RequestParam requestParam = ANNOTATION.cast(annotation);
		String name = requestParam.value();
		if (emptyToNull(name) != null) {
			context.setParameterName(name);

			MethodMetadata data = context.getMethodMetadata();
			Collection<String> query = context.setTemplateParameter(name,
					data.template().queries().get(name));
			data.template().query(name, query);
		} else {
			// supports `Map` types
			MethodMetadata data = context.getMethodMetadata();
			data.queryMapIndex(context.getParameterIndex());
		}
		return true;
	}

说明spring-cloud-feign处理@RequestParam和Spring mvc的不一样，Spring mvc在@RequestParam的value为空的时候反射得到参数的名字作为value

解决方案: 给@RequestParam加上value