fix: merging mistake.

Author: zhumin8

oauth2_http/java/com/google/auth/oauth2/ImpersonatedCredentials.java

@@ -44,7 +44,6 @@
 import com.google.api.client.json.JsonObjectParser;
 import com.google.api.client.util.GenericData;
 import com.google.auth.CredentialTypeForMetrics;
-import com.google.auth.Credentials;
 import com.google.auth.ServiceAccountSigner;
 import com.google.auth.http.HttpCredentialsAdapter;
 import com.google.auth.http.HttpTransportFactory;
@@ -502,17 +501,6 @@ public String getUniverseDomain() throws IOException {
     return this.sourceCredentials.getUniverseDomain();
   }
 
-  @Override
-  boolean isDefaultUniverseDomain() {
-    try {
-      return getUniverseDomain().equals(Credentials.GOOGLE_DEFAULT_UNIVERSE);
-    } catch (IOException e) {
-      // super method does not throw IOException, so wrap it here.
-      // This should not happen for this credential type.
-      throw new IllegalStateException(e);
-    }
-  }
-
   @Override
   public AccessToken refreshAccessToken() throws IOException {
     if (this.sourceCredentials.getAccessToken() == null) {
@@ -789,12 +777,6 @@ public Calendar getCalendar() {
       return this.calendar;
     }
 
-    @Override
-    public Builder setUniverseDomain(String universeDomain) {
-      super.setUniverseDomain(universeDomain);
-      return this;
-    }
-
     @Override
     public ImpersonatedCredentials build() {
       try {