Fix ClassCastException in doeditcolourscheme.action with Struts

2022-08-02 08:35:39,933 ERROR [http-nio-8080-exec-8] [apache.struts2.dispatcher.DefaultDispatcherErrorHandler] sendErrorResponse Exception occurred during processing request: class org.apache.struts2.dispatcher.Parameter$Request cannot be cast to class [Ljava.lang.String; (org.apache.struts2.dispatcher.Parameter$Request is in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader @3c3562c0; [Ljava.lang.String; is in module java.base of loader 'bootstrap')
 -- url: /confluence/admin/doeditcolourscheme.action | userName: admin | referer: http://localhost:8080/confluence/admin/lookandfeel.action | traceId: 898b486971dd9e56
java.lang.ClassCastException: class org.apache.struts2.dispatcher.Parameter$Request cannot be cast to class [Ljava.lang.String; (org.apache.struts2.dispatcher.Parameter$Request is in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader @3c3562c0; [Ljava.lang.String; is in module java.base of loader 'bootstrap')
    at com.atlassian.confluence.admin.actions.lookandfeel.ColourSchemeAction.getFromColourMap(ColourSchemeAction.java:90)
    at com.atlassian.confluence.admin.actions.lookandfeel.ColourSchemeAction.validateAndPopulateColourScheme(ColourSchemeAction.java:83)
    at com.atlassian.confluence.admin.actions.lookandfeel.ColourSchemeAction.execute(ColourSchemeAction.java:25)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)