projectOperations.addPlugin adds empty <id/> and <phase/> tags per default which let maven ignore the build plugin

when updating maven build plugin the configuration element adds some invalid maven markup, so that maven ignores the build plugin:
empty tags (id, phase) are invalid:
<execution>
<id/>
<phase/>
<goals>
<goal>compile</goal>
<goal>test-compile</goal>
</goals>
</execution>

Patch: MavenProjectMetadataProvider

final String id = execution.getId();
if (id !=null && !id.isEmpty())

{ Element executionId = document.createElement("id"); executionId.setTextContent(id); executionElement.appendChild(executionId); }

final String phase = execution.getPhase();
if (phase!=null && !phase.isEmpty())

{ Element executionPhase = document.createElement("phase"); executionPhase.setTextContent(phase); executionElement.appendChild(executionPhase); }