fix: provide lsp4j source bundles on p2 update site

Fixes #1519

Author: iloveeclipse

pom.xml

@@ -254,6 +254,14 @@
 							<defaultP2Metadata>false</defaultP2Metadata>
 						</configuration>
 					</plugin>
+					<plugin>
+						<groupId>org.eclipse.tycho</groupId>
+						<artifactId>tycho-p2-repository-plugin</artifactId>
+						<version>${tycho-version}</version>
+						<configuration>
+							<includeAllSources>true</includeAllSources>
+						</configuration>
+					</plugin>
 				</plugins>
 			</build>
 		</profile>