Fix issue in DexPool with blank parameter annotations
diff --git a/dexlib2/src/main/java/org/jf/dexlib2/writer/DexWriter.java b/dexlib2/src/main/java/org/jf/dexlib2/writer/DexWriter.java
index 6033f86..9c979b7 100644
--- a/dexlib2/src/main/java/org/jf/dexlib2/writer/DexWriter.java
+++ b/dexlib2/src/main/java/org/jf/dexlib2/writer/DexWriter.java
@@ -609,7 +609,11 @@
 
                         writer.writeInt(parameterAnnotations.size());
                         for (AnnotationSetKey annotationSetKey: parameterAnnotations) {
-                            writer.writeInt(annotationSetSection.getItemOffset(annotationSetKey));
+                            if (annotationSetSection.getAnnotations(annotationSetKey).size() > 0) {
+                                writer.writeInt(annotationSetSection.getItemOffset(annotationSetKey));
+                            } else {
+                                writer.writeInt(NO_OFFSET);
+                            }
                         }
                     }
                 }