fix build on jdk21-25

[ennerf]

This PR fixes the non-test compilation for jdk17 / jdk21 / jdk25: mvn clean package -DskipTests. I tried getting tests to run as well, but that's going to be an enormous rabbit hole.

Changes

• added @dlemmermann's fix for Deque in Building with Java 21 #655
• fixed various jdk21 javadoc issues like removing @inheritDoc from non-existant documentation, and references to classes that were not accessible.
• for jdk25 I added a profile to disable javadoc entirely because the samples module crashes and I really don't know why.

Jdk25 Javadoc error

[INFO] Reactor Summary for chartfx-parent master-SNAPSHOT:
[INFO]
[INFO] chartfx-parent ..................................... SUCCESS [  0.821 s]
[INFO] chartfx-bench ...................................... SUCCESS [  2.179 s]
[INFO] chartfx-generate ................................... SUCCESS [  0.487 s]
[INFO] chartfx-dataset .................................... SUCCESS [  5.265 s]
[INFO] chartfx_math ....................................... SUCCESS [  3.487 s]
[INFO] chartfx-chart ...................................... SUCCESS [  6.544 s]
[INFO] chartfx-acc ........................................ SUCCESS [  1.545 s]
[INFO] chartfx-samples .................................... FAILURE [  2.726 s]
[INFO] chartfx-report ..................................... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  23.189 s
[INFO] Finished at: 2026-02-25T20:35:12+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:3.6.3:jar (attach-javadocs) on project samples: MavenReportException: Error while generating Javadoc:
[ERROR] Exit code: 1
[ERROR] error: An internal exception has occurred.
[ERROR]         (java.lang.NullPointerException: Cannot invoke "com.sun.source.util.DocTreePath.getTreePath()" because "path" is null)
[ERROR] Please file a bug against the javadoc tool via the Java bug reporting page
[ERROR] (https://bugreport.java.com) after checking the Bug Database (https://bugs.java.com)
[ERROR] for duplicates. Include error messages and the following diagnostic in your report. Thank you.
[ERROR] java.lang.NullPointerException: Cannot invoke "com.sun.source.util.DocTreePath.getTreePath()" because "path" is null
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.tool.JavadocLog.getDiagnosticSource(JavadocLog.java:660)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.tool.JavadocLog.print(JavadocLog.java:247)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.Messages.report(Messages.java:238)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.Messages.warning(Messages.java:158)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.taglets.SeeTaglet.lambda$seeTagOutput$0(SeeTaglet.java:180)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.taglets.LinkTaglet.linkSeeReferenceOutput(LinkTaglet.java:191)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.taglets.SeeTaglet.seeTagOutput(SeeTaglet.java:174)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.taglets.SeeTaglet.seeTagOutput(SeeTaglet.java:108)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.taglets.SeeTaglet.getAllBlockTagOutput(SeeTaglet.java:92)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.taglets.TagletWriter.getBlockTagOutput(TagletWriter.java:263)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.getBlockTagOutput(HtmlDocletWriter.java:396)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.getBlockTagOutput(HtmlDocletWriter.java:382)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.addTagsInfo(HtmlDocletWriter.java:368)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.PropertyWriter.addTags(PropertyWriter.java:226)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.PropertyWriter.buildTagInfo(PropertyWriter.java:148)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.PropertyWriter.buildPropertyDoc(PropertyWriter.java:89)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.PropertyWriter.buildDetails(PropertyWriter.java:65)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.ClassWriter.buildMemberDetails(ClassWriter.java:337)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.ClassWriter.buildClassDoc(ClassWriter.java:137)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.ClassWriter.buildPage(ClassWriter.java:114)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDoclet.generateClassFiles(HtmlDoclet.java:425)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.generateClassFiles(AbstractDoclet.java:246)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDoclet.generateClassFiles(HtmlDoclet.java:211)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.generateFiles(AbstractDoclet.java:179)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDoclet.generateFiles(HtmlDoclet.java:353)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.run(AbstractDoclet.java:82)
[ERROR]         at jdk.javadoc/jdk.javadoc.doclet.StandardDoclet.run(StandardDoclet.java:109)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.tool.Start.parseAndExecute(Start.java:591)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:399)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:348)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.tool.Main.execute(Main.java:57)
[ERROR]         at jdk.javadoc/jdk.javadoc.internal.tool.Main.main(Main.java:46)
[ERROR] 1 error

[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.5% Duplication on New Code

See analysis details on SonarQube Cloud