Fix header style issue caught by copybara (#5923)

Author: paulb777

Example/CoreDiagnostics/Tests/FIRCoreDiagnosticsTest.m

@@ -19,13 +19,13 @@
 #import <UIKit/UIKit.h>
 #endif  // TARGET_OS_IOS || TARGET_OS_TV
 
-#import <GoogleUtilities/GULAppEnvironmentUtil.h>
 #import <OCMock/OCMock.h>
 #import <nanopb/pb_decode.h>
 #import <nanopb/pb_encode.h>
 #import "GoogleDataTransport/GDTCORLibrary/Public/GDTCOREvent.h"
 #import "GoogleDataTransport/GDTCORLibrary/Public/GDTCOREventDataObject.h"
 #import "GoogleDataTransport/GDTCORLibrary/Public/GDTCORTransport.h"
+#import "GoogleUtilities/Environment/Private/GULAppEnvironmentUtil.h"
 #import "GoogleUtilities/Environment/Private/GULHeartbeatDateStorage.h"
 #import "GoogleUtilities/UserDefaults/Private/GULUserDefaults.h"
 #import "Interop/CoreDiagnostics/Public/FIRCoreDiagnosticsData.h"