Issue #13043: Modify link javadoc tag reference to be optional

[0xbakry]

Solves https://github.com/checkstyle/checkstyle/issues/13043

CLI:

$ cat config1.xml
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
        "https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name = "Checker">
    <property name="charset" value="UTF-8"/>

    <module name="TreeWalker">
       <module name="NonEmptyAtclauseDescription"/>
    </module>

</module>

$ cat Test1.java
public class Test1 {

  /**
   * {@link}
   * {@linkplain}
   */
  public void method(String a)
  {

  }
}

$ java -jar checkstyle-10.10.1-SNAPSHOT-all.jar -c config1.xml Test1.java
Starting audit...
Audit done.

Diff Regression projects: https://gist.githubusercontent.com/0xbakry/7853843aa3d69aee301d7a8d62d08ebb/raw/65a7d6bee0ad8ad789c17f778ce7d8b0056ae28b/my_projects Diff Regression config: https://gist.githubusercontent.com/0xbakry/a1fcb13eef42f29de8ff500892f34166/raw/beceb87d12215501a53ffc29e87f6c0af78f588c/config_check.xml

[0xbakry]

GitHub, generate report

[github-actions[bot]]

https://checkstyle-diff-reports.s3.us-east-2.amazonaws.com/642ace9_2023185553/reports/diff/index.html

[nrmancuso]

@0xbakry do you plan to continue work on this PR?

[0xbakry]

@0xbakry do you plan to continue work on this PR?

Yeah, I'm a little busy with some work right now, but I'm planning to continue working on the project soon.

[rnveach]

Needs to be rebased.

[romani]

if no activity before 1 october , we will close PR to let somebody else to finish this update by reusage of this code

@0xbakry , please find time to finish update, looks like a little is left to be done

[0xbakry]

Sorry for the delay, I don't have access to my laptop most of the time, so I'm closing this PR to let someone else work on it.

[romani]

single commit please

[romani]

Here is response https://github.com/checkstyle/checkstyle/pull/13046#discussion_r1564931186 from author, let's wait a bit more. Thanks a lot for coming back to it.

[romani]

@0xbakry , please find time to finish PR