Update MapBinder so it fails on duplicate bindings with a more descriptive error message, including all the keys that had duplicates and where the duplicate bindings were bound.  Example error message that has 'a' bound twice and 'b' bound twice:

1) Map injection failed due to duplicated key "a", from bindings at:
	com.google.inject.multibindings.MapBinderTest.configure(MapBinderTest.java:337) (via modules: com.google.inject.multibindings.MapBinderTest$1Main -> com.google.inject.multibindings.MapBinderTest$1Module1)
	com.google.inject.multibindings.MapBinderTest.configure(MapBinderTest.java:344) (via modules: com.google.inject.multibindings.MapBinderTest$1Main -> com.google.inject.multibindings.MapBinderTest$1Module2)

 and key: "b", from bindings at:
	com.google.inject.multibindings.MapBinderTest.configure(MapBinderTest.java:345) (via modules: com.google.inject.multibindings.MapBinderTest$1Main -> com.google.inject.multibindings.MapBinderTest$1Module2)
	com.google.inject.multibindings.MapBinderTest.configure(MapBinderTest.java:352) (via modules: com.google.inject.multibindings.MapBinderTest$1Main -> com.google.inject.multibindings.MapBinderTest$1Module3)

  at com.google.inject.multibindings.MapBinder.initialize(MapBinder.java:380)
  at com.google.inject.multibindings.MapBinderTest.configure(MapBinderTest.java:357) (via modules: com.google.inject.multibindings.MapBinderTest$1Main -> com.google.inject.multibindings.MapBinder$RealMapBinder)
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=62865462
2 files changed