[fixes #3748] Patch SourceTypeConverter to avoid parsing empty strings

test/eclipse/resource/noerrors/synchronizedUsage/ClassWithSynchronized.java

@@ -0,0 +1,9 @@
+package pkg;
+
+import lombok.Synchronized;
+
+public class ClassWithSynchronized {
+	@Synchronized
+	public void test() {
+	}
+}