Issue with com.opensymphony.xwork.util.XWorkList on Confluence 8.0

Hi
We are having issue with Confluence 8.0 compatibility for our app. We are looking for replacement to com.opensymphony.xwork.util.XWorkList class. Ww tried to replace it with com.opensymphony.xwork2.conversion.impl.XWorkList but it is throwing null pointer exception in 7.x version though working fine in 8.0 . Has any one faced or fixed similar issue ? Thanks

To add more details to the above exception
Line: 177 - com/opensymphony/xwork2/conversion/impl/XWorkList.java:177:-1
at com.opensymphony.xwork2.conversion.impl.XWorkList.get(XWorkList.java:169)
at ognl.ListPropertyAccessor.getProperty(ListPropertyAccessor.java:68)
at ognl.OgnlRuntime.getProperty(OgnlRuntime.java:1600)
at ognl.ASTProperty.getValueBody(ASTProperty.java:96)
at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:171)
at ognl.SimpleNode.getValue(SimpleNode.java:193)
at ognl.ASTChain.setValueBody(ASTChain.java:168)
at ognl.SimpleNode.evaluateSetValueBody(SimpleNode.java:180)
at ognl.SimpleNode.setValue(SimpleNode.java:230)
at ognl.Ognl.setValue(Ognl.java:476)
at com.opensymphony.xwork.util.OgnlUtil.setValue(OgnlUtil.java:189)
at com.opensymphony.xwork.util.OgnlValueStack.setValue(OgnlValueStack.java:113)
at com.opensymphony.xwork.util.OgnlValueStack.setValue(OgnlValueStack.java:97)
at com.atlassian.xwork.interceptors.SafeParametersInterceptor.before(SafeParametersInterceptor.java:145)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:34)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.xwork.interceptors.TransactionalInvocation.invokeAndHandleExceptions(TransactionalInvocation.java:71)
at com.atlassian.xwork.interceptors.TransactionalInvocation.invokeInTransaction(TransactionalInvocation.java:57)
at com.atlassian.xwork.interceptors.XWorkTransactionInterceptor.intercept(XWorkTransactionInterceptor.java:56)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.xwork.SetupIncompleteInterceptor.intercept(SetupIncompleteInterceptor.java:61)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.atlassian.confluence.security.interceptors.SecurityHeadersInterceptor.intercept(SecurityHeadersInterceptor.java:39)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:115)
at com.atlassian.confluence.servlet.ConfluenceServletDispatcher.serviceAction(ConfluenceServletDispatcher.java:56)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:199)

at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.NullPointerException
at com.opensymphony.xwork2.conversion.impl.XWorkList.getObjectFactory(XWorkList.java:177)
at com.opensymphony.xwork2.conversion.impl.XWorkList.get(XWorkList.java:167)
… 337 more