Fix MavenReportException problem

[steverao]

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Which Component
eg. Nacos Config, RocketMQ

Is your feature request related to a problem? Please describe.
When I run command as follows mvn clean install under root directory in branch of 2.2.x, it will report warning information as below:

MavenReportException: Error while generating Javadoc: 
Exit code: 1 - /Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/parser/AbstractPropertySourceLoader.java:37: error: self-closing element not allowed
 * 1.inherit {@link AbstractPropertySourceLoader} ;<br/>
                                                   ^
/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/parser/AbstractPropertySourceLoader.java:39: error: self-closing element not allowed
 * {@code org.springframework.boot.env.PropertySourceLoader=..}; <br/>
                                                                 ^
/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/parser/NacosJsonPropertySourceLoader.java:76: warning: no @param for map
        protected Map<String, Object> reloadMap(Map<String, Object> map) {
                                      ^
/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/parser/NacosJsonPropertySourceLoader.java:76: warning: no @return
        protected Map<String, Object> reloadMap(Map<String, Object> map) {
                                      ^
/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/parser/NacosXmlPropertySourceLoader.java:43: error: unknown tag: conde
 * ({@conde DOCTYPE}) THE XML in a way that makes it difficult to customize the
    ^

Command line was: /Library/Java/JavaVirtualMachines/jdk1.8.0_291.jdk/Contents/Home/jre/../bin/javadoc @options @packages

Refer to the generated Javadoc files in '/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-nacos-config/target/apidocs' dir.

MavenReportException: Error while generating Javadoc: 
Exit code: 1 - warning: unknown enum constant When.MAYBE
  reason: class file for javax.annotation.meta.When not found
/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-stream-rocketmq/src/main/java/com/alibaba/cloud/stream/binder/rocketmq/properties/RocketMQConsumerProperties.java:52: error: self-closing element not allowed
         * <p/>
           ^
/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-stream-rocketmq/src/main/java/com/alibaba/cloud/stream/binder/rocketmq/properties/RocketMQConsumerProperties.java:54: error: self-closing element not allowed
         * <p/>
           ^

Command line was: /Library/Java/JavaVirtualMachines/jdk1.8.0_291.jdk/Contents/Home/jre/../bin/javadoc @options @packages

Refer to the generated Javadoc files in '/Users/raozihao/IdeaProjects/actual-project/spring-cloud-alibaba/spring-cloud-alibaba-starters/spring-cloud-starter-stream-rocketmq/target/apidocs' dir.

Describe the solution you'd like
We need to fix the problem in branch of 2.2.x and check whether there are same problems in branch of 2021.x.

[kaori-seasons]

I would like to follow up on this issue