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Describe the bug

When publish/rollback namespaces with gray release, the operation failed with the error message java.lang.IllegalStateException: Expected BEGIN_ARRAY but was NUMBER at line 1 column 20 path $..

The stacktrace in server log is as follows:

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was NUMBER at line 1 column 20 path $.
	at com.google.gson.Gson.fromJson(Gson.java:975)
	at com.google.gson.Gson.fromJson(Gson.java:928)
	at com.google.gson.Gson.fromJson(Gson.java:877)
	at com.ctrip.framework.apollo.biz.service.ReleaseService.getBranchReleaseKeys(ReleaseService.java:333)

To Reproduce
Steps to reproduce the behavior:

1. Create a grayscale version for some namespace, e.g. application
2. Change some value in the grayscale version and publish the grayscale version
3. Change some value in the main version
4. Publish or rollback the main version, then you will see the error

Expected behavior
The publish/rollback operations should work with no error.

Screenshots

Additional Details & Logs

• Version: 2.1.0-SNAPSHOT