Jira Plugin not working in 9.7.X while working in 8.20.X

Failing

<?xml version="1.0" encoding="UTF-8"?>

<atlassian-plugin key="${atlassian.plugin.key}" name="${project.name}" plugins-version="2"> 
  <plugin-info> 
    <description>${project.description}</description>  
    <version>${project.version}</version>  
    <vendor name="${project.organization.name}" url="${project.organization.url}"/>  
    <param name="plugin-icon">images/pluginIcon.png</param>  
    <param name="plugin-logo">images/pluginLogo.png</param> 
    <param name="atlassian-data-center-status">compatible</param>
    <param name="atlassian-data-center-compatible">true</param>
    <param name="plugin-type">both</param>
  </plugin-info>  
  <!-- add our i18n resource -->  
  <resource type="i18n" name="i18n" location="aq-jira-plugin"/>  
  <!-- add our web resources -->  
  <web-resource key="aq-jira-plugin-resources" name="aq-jira-plugin Web Resources"> 
    <dependency>com.atlassian.auiplugin:ajs</dependency>  
    <dependency>com.atlassian.auiplugin:aui-select2</dependency>  
    <resource type="download" name="aq-jira-plugin.css" location="/css/aq-jira-plugin.css"/>  
    <resource type="download" name="aq-jira-plugin.js" location="/js/aq-jira-plugin.js"/>  
    <resource type="download" name="images/" location="/images"/>  
    <context>aq-jira-plugin</context> 
  </web-resource>  
  <servlet name="Accelq Connect" i18n-name-key="accelq-connect.name" key="accelq-connect" class="com.accelq.plugins.jira.servlet.AccelqConnect"> 
    <description key="accelq-connect.description">The Accelq Connect Plugin</description>  
    <url-pattern>/accelq</url-pattern> 
  </servlet>  
  <web-item name="AccelQ Nav WebItem" i18n-name-key="aq-nav-web-item.name" key="aq-nav-web-item" section="system.top.navigation.bar" weight="110"> 
    <description key="aq-nav-web-item.description">The AccelQ Nav WebItem Plugin</description>  
    <!--<context-provider class="com.accelq.plugins.jira.AQNavContextProvider"/>-->  
    <condition class="com.atlassian.jira.plugin.webfragment.conditions.UserLoggedInCondition"/>  
    <label key="aq-nav-web-item.label"/>  
    <link linkId="aq-nav-web-item-link">/plugins/servlet/accelq</link>  
    <dependency>com.atlassian.auiplugin:aui-select</dependency> 
  </web-item>  
  <web-section name="AccelQ Configuration" i18n-name-key="aq-config.name" key="aq-config" location="admin_plugins_menu" weight="110"> 
    <description key="aq-config.description">The AccelQ Configuration Plugin</description>  
    <label key="aq-config.label"/> 
  </web-section>  
  <web-item name="AccelQ plugin Configuration" i18n-name-key="aq-plugin-config.name" key="aq-plugin-config" section="admin_plugins_menu/aq-config"> 
    <description key="aq-plugin-config.description">The AccelQ plugin Configuration Plugin</description>  
    <label key="aq-plugin-config.label"/>  
    <link linkId="aq-plugin-config-link">/secure/AQAdminConfigAction.jspa</link> 
  </web-item>  
  <webwork1 key="aq-admin-config" name="Administration Configuration" i18n-name-key="aq-admin-config.name" class="java.lang.Object"> 
    <description key="aq-admin-config.desc">The Administration Configuration Plugin</description>  
    <actions> 
      <action name="com.accelq.plugins.jira.webwork.AQAdminConfigAction" alias="AQAdminConfigAction"> 
        <view name="success">/templates/aq-admin-config/aq-admin-config.vm</view>  
        <view name="edit">/templates/aq-admin-config/aq-admin-config-edit.vm</view>  
        <view name="save">/templates/aq-admin-config/aq-admin-config.vm</view> 
      </action> 
    </actions> 
  </webwork1>  
  <web-panel name="AQIssueConnect" i18n-name-key="aq-issue-connect.name" key="aq-issue-connect" location="atl.jira.view.issue.left.context" weight="400"> 
    <condition class="com.accelq.plugins.jira.conditions.AQTracabilityDisplayCondition"/>  
    <description key="aq-issue-connect.description">The AQIssueConnect Plugin</description>  
    <context-provider class="com.accelq.plugins.jira.providers.AQIssueConnect"/>  
    <resource name="view" type="velocity" location="templates/aq-issue-view/aq-issue-view.vm"/>  
    <label key="aq-issue-view.title"/> 
  </web-panel>  
</atlassian-plugin>

Can you point me to article where all changes are clearly mentioned? And are these changes gonna break on Jira 8.X customers?

https://confluence.atlassian.com/jiracore/preparing-for-jira-9-0-1115661092.html
in section “Verification of Jira web action request methods”.

The thread I quoted is about the way to have a single source to support both Jira 8 and 9.