Bug 354388 - NPE in FeatureInputContext#synchronizeModel

Added null check for IDocument argument

Change-Id: Ifa28bf0dfce1e3d39bc8aad8be459757609927d7
Signed-off-by: Alexander Fedorov <alexander.fedorov@arsysop.ru>
diff --git a/ui/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/editor/feature/FeatureInputContext.java b/ui/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/editor/feature/FeatureInputContext.java
index 532c5da..bbd6661 100644
--- a/ui/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/editor/feature/FeatureInputContext.java
+++ b/ui/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/editor/feature/FeatureInputContext.java
@@ -135,21 +135,17 @@
 
 	@Override
 	protected boolean synchronizeModel(IDocument doc) {
+		if (doc == null) {
+			return false;
+		}
 		IFeatureModel model = (IFeatureModel) getModel();
-
-		boolean cleanModel = true;
 		String text = doc.get();
-		InputStream stream = new ByteArrayInputStream(text.getBytes(StandardCharsets.UTF_8));
-		try {
+		try (InputStream stream = new ByteArrayInputStream(text.getBytes(StandardCharsets.UTF_8))) {
 			model.reload(stream, false);
-		} catch (CoreException e) {
-			cleanModel = false;
+		} catch (CoreException | IOException e) {
+			return false;
 		}
-		try {
-			stream.close();
-		} catch (IOException e) {
-		}
-		return cleanModel;
+		return true;
 	}
 
 	@Override