plugins/devkit/testData/codeInsight/ExtensionsHighlighting.xml

<idea-plugin>
    <id>com.intellij.myPlugin</id>
    <extensionPoints>
        <extensionPoint name="foo.bar"/>
        <extensionPoint name="ext" interface="java.lang.Runnable"/>
        <extensionPoint name="deprecatedEP" interface="foo.MyDeprecatedEP"/>
    </extensionPoints>

  <depends>com.intellij.custom</depends>

    <extensions defaultExtensionNs="com.intellij">
        <<error descr="'implementation' attribute should be defined">myPlugin.ext</error>/>
        <myPlugin.ext implementation="<error descr="Interface is not allowed">java.lang.Runnable</error>"/>
        <myPlugin.ext implementation="<error descr="'java.util.concurrent.TimeUnit' is not assignable to 'java.lang.Runnable'"><error descr="Enum is not allowed">java.util.concurrent.TimeUnit</error></error>"/>
        <myPlugin.ext implementation="<error descr="'java.lang.String' is not assignable to 'java.lang.Runnable'">java.lang.String</error>"/>

        <<error descr="Deprecated EP">myPlugin.deprecatedEP</error> implementation="foo.MyDeprecatedEPImpl"/>

        <myPlugin.foo.bar/>
        <completion.contributor/>
        <custom.custom/>
        <indirect.indirect/>
        <<error descr="Element custom.error is not allowed here">custom.error</error>/>
    </extensions>
</idea-plugin>