createPlugin

 MavenPluginFacet mavenPluginFacet = getProject().getFacet(MavenPluginFacet.class);

      int nrOfPlugins = getNumberOfPlugins();
      MavenPluginBuilder plugin = MavenPluginBuilder.create()
                .setDependency(
                         DependencyBuilder.create()
                                  .setGroupId("org.apache.maven.plugins")
                                  .setArtifactId("maven-site-plugin")
                                  .setVersion("3.0")
                );
       MavenPluginAdapter mvnPlugin = new MavenPluginAdapter(plugin);

createProfile

MavenCoreFacet facet = project.getFacet(MavenCoreFacet.class);

      Profile profile = new Profile();
      profile.setId(profileId);

       profile.getBuild().addPlugin(theplugin);
     
      Model pom = facet.getPOM();
      pom.addProfile(profile);
       
      facet.setPOM(pom);