Make get(0) safe and document it.

org.fortiss.tooling.kernel/trunk/src/org/fortiss/tooling/kernel/utils/EcoreSerializerBase.java

@@ -42,7 +42,7 @@ import org.osgi.framework.Bundle;
  * @author barner
  * @author $Author$
  * @version $Rev$
- * @ConQAT.Rating GREEN Hash: 9B5AB77EC13C4D7553AEF2AF60CA06D7
+ * @ConQAT.Rating YELLOW Hash: 1EB8B12E46C5D4738A9D552205E56A0B
  */
 public abstract class EcoreSerializerBase<R extends EObject> {
 
@@ -111,6 +111,10 @@ public abstract class EcoreSerializerBase<R extends EObject> {
 		ResourceSet resourceSet = createResourceSet();
 		Resource resource = resourceSet.getResource(uri, true);
 
+		if(resource.getContents().isEmpty()) {
+			return null;
+		}
+		// get(0) is guaranteed to be safe
 		return getRootElement(resource.getContents().get(0));
 	}