Exposes the currently registered extensions for a message and removes the…

Exposes the currently registered extensions for a message and removes the internal sortedExtensionsInUse

objectivec/GPBMessage.h

@@ -275,6 +275,9 @@ CF_EXTERN_C_END
 /// Return the descriptor for the message.
 - (GPBDescriptor *)descriptor;
 
+/// Returns an array with the currently set GPBExtensionDescriptors.
+- (NSArray *)extensionsCurrentlySet;
+
 /// Test to see if the given extension is set on the message.
 - (BOOL)hasExtension:(GPBExtensionDescriptor *)extension;
 

objectivec/GPBMessage.m

@@ -1777,11 +1777,6 @@ static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) {
   }
 }
 
-- (NSArray *)sortedExtensionsInUse {
-  return [[extensionMap_ allKeys]
-      sortedArrayUsingSelector:@selector(compareByFieldNumber:)];
-}
-
 - (void)setExtension:(GPBExtensionDescriptor *)extension value:(id)value {
   if (!value) {
     [self clearExtension:extension];

objectivec/GPBMessage_PackagePrivate.h

@@ -78,10 +78,6 @@ typedef struct GPBMessage_Storage *GPBMessage_StoragePtr;
 // returns nil if the extension is not set)
 - (id)getExistingExtension:(GPBExtensionDescriptor *)extension;
 
-// Returns an array of GPBExtensionDescriptor* for all the extensions currently
-// in use on the message.  They are sorted by field number.
-- (NSArray *)sortedExtensionsInUse;
-
 // Parses a message of this type from the input and merges it with this
 // message.
 //

objectivec/GPBUtilities.m

@@ -1472,7 +1472,8 @@ static void AppendTextFormatForMessage(GPBMessage *message,
   NSUInteger fieldCount = fieldsArray.count;
   const GPBExtensionRange *extensionRanges = descriptor.extensionRanges;
   NSUInteger extensionRangesCount = descriptor.extensionRangesCount;
-  NSArray *activeExtensions = [message sortedExtensionsInUse];
+  NSArray *activeExtensions = [[message extensionsCurrentlySet]
+      sortedArrayUsingSelector:@selector(compareByFieldNumber:)];
   for (NSUInteger i = 0, j = 0; i < fieldCount || j < extensionRangesCount;) {
     if (i == fieldCount) {
       AppendTextFormatForMessageExtensionRange(