Add custom exceptions to constants class as well

src/main/java/com/nextcloud/android/sso/Constants.java

@@ -7,4 +7,7 @@ public class Constants {
     public final static String SSO_TOKEN = "token";
     public final static String SSO_SERVER_URL = "server_url";
 
+    // Custom Exceptions
+    public static final String EXCEPTION_INVALID_TOKEN = "CE_1";
+    public static final String EXCEPTION_ACCOUNT_NOT_FOUND = "CE_2";
 }

src/main/java/com/nextcloud/android/sso/aidl/NextcloudRequest.java

@@ -27,8 +27,6 @@ import java.util.Map;
 public class NextcloudRequest implements Serializable {
 
     private static final long serialVersionUID = 215521212534236L; //assign a long value
-    public static final String EXCEPTION_INVALID_TOKEN = "CE_1";
-    public static final String EXCEPTION_ACCOUNT_NOT_FOUND = "CE_2";
 
     public String method;
     public Map<String, List<String>> header = new HashMap<>();