Fix for build failing when build dir is empty

Author: smehrbrodt

CHANGELOG.md

@@ -4,6 +4,7 @@
 * #72 Fix running javamaker with spaces in project path
 * Load description.xml editor even when locale is missing
 * Remove crashreport service (Service no longer exists)
+* Fix build with empty `build` directory
 
 ## 3.0.0
 * Python support for extension development

java/source/org/libreoffice/ide/eclipse/java/JavaBuilder.java

@@ -128,6 +128,13 @@ public IFile createLibrary(IUnoidlProject pUnoProject) throws Exception {
 
         IFolder buildDir = pUnoProject.getFolder(pUnoProject.getBuildPath());
         buildDir.accept(visitor);
+        
+        // Adding the source directory is not strictly necessary
+        // (and it has practically no impact on the generated jar).
+        // But if the build path is empty, the build fails.
+        // So the contract seems to be that setElements must be called with a non-empty list of files.
+        IFolder sourceDir = pUnoProject.getFolder(pUnoProject.getSourcePath());
+        sourceDir.accept(visitor);
         description.setElements(visitor.getFiles());
 
         // Create the Jar file