fix: exclude samples from Maven Central publishing (#3537)

* fix: exclude the Kotlin sample from Maven Central publishing

The module has no Java sources, so maven-javadoc-plugin attaches no
javadoc jar to it and Central rejects the whole deployment with
"Javadocs must be provided but not found in entries", which is what
broke the 5.5.1 release. It only exists as a Kotlin interop E2E test,
so keep it out of the published bundle.

* fix: exclude all samples from Maven Central publishing

Replaces the skipPublishing property on the Kotlin sample with an
excludeArtifacts list on central-publishing-maven-plugin, so the
exclusion lives next to the publishing configuration, and extends it to
every sample module: they are demos and end-to-end tests, not artifacts
to depend on.

Author: csviri

pom.xml

@@ -642,6 +642,20 @@
               <tokenAuth>true</tokenAuth>
               <autoPublish>true</autoPublish>
               <waitUntil>published</waitUntil>
+              <!-- The samples are demos and end-to-end tests, not artifacts to depend on, so they
+                   are not published. The Kotlin one could not be published anyway: it has no Java
+                   sources, so no javadoc jar is attached to it and Central rejects the whole
+                   deployment with "Javadocs must be provided but not found in entries". -->
+              <excludeArtifacts>
+                <excludeArtifact>sample-operators</excludeArtifact>
+                <excludeArtifact>sample-controller-namespace-deletion</excludeArtifact>
+                <excludeArtifact>sample-kotlin-operator</excludeArtifact>
+                <excludeArtifact>sample-leader-election</excludeArtifact>
+                <excludeArtifact>sample-mysql-schema-operator</excludeArtifact>
+                <excludeArtifact>sample-operations</excludeArtifact>
+                <excludeArtifact>sample-tomcat-operator</excludeArtifact>
+                <excludeArtifact>sample-webpage-operator</excludeArtifact>
+              </excludeArtifacts>
             </configuration>
           </plugin>
         </plugins>