Fixed: [  Issue 27  ]  Minimum proposed index for enum literals should be zero
https://code.google.com/p/protobuf-dt/issues/detail?id=27

com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java

diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java
index 9d8d8c0..f18820e 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java
@@ -24,8 +24,9 @@
 public class Literals {
 
   public int calculateIndexOf(Literal l) {
-    int index = 0;
-    for (EObject o : l.eContainer().eContents()) {
+    int index = -1;
+    EObject container = l.eContainer();
+    for (EObject o : container.eContents()) {
       if (o == l || !(o instanceof Literal)) continue;
       Literal c = (Literal) o;
       index = max(index, c.getIndex());