Fix build by adding missing update site to jdt.ls.extension pom

Seems like stuff depending on jboss APT m2e extension was added to
jdt.ls. So if we do not add this update site our buld fails resolving
target platform for our jdt.ls.extension.

headless-services/jdt-ls-extension/pom.xml

@@ -31,6 +31,12 @@
 			<!-- <url>${jdt.ls.updatesite}</url> -->
 			<url>http://download.eclipse.org/jdtls/snapshots/repository/latest/</url>
 		</repository>
+		<repository>
+			<id>jboss-apt</id>
+			<layout>p2</layout>
+			<!--URL copied from jdt.ls target platform file, needed to satisfy some of its dependencies -->
+			<url>http://download.jboss.org/jbosstools/updates/m2e-extensions/m2e-apt/1.5.0-2018-04-06_03-47-50-H10</url>
+		</repository>
 	</repositories>
 	<build>
 		<plugins>