Version of GWT

[VikasGupta1993]

I have used the SmartGWT version as 12.1-p20200813 so I want to know the following version compatible with this version.

-> gwt-maven-plugin version ??
->gwt-servlet ??
->gwt-user ??

Please help me

[VikasGupta1993]

I am also getting below exception or warning:-

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.google.gwt.user.client.rpc.core.java.util.LinkedHashMap_CustomFieldSerializer (file:/D:/VikasGupta/Tools/PMPRO_UMAN_Tomcat8.5.43/apache-tomcat-8.5.43/webapps/Uman/WEB-INF/lib/gwt-servlet-2.9.0.jar) to field java.util.LinkedHashMap.accessOrder
WARNING: Please consider reporting this to the maintainers of com.google.gwt.user.client.rpc.core.java.util.LinkedHashMap_CustomFieldSerializer
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

Please provide me a solution