Check for a behavior change with resource reference injection target merging

In the Servlet 3.0 specification, the <injection-target> elements of a resource reference that is defined in a web-fragment.xml file are added to the parent web.xml file only if the web.xml resource reference definition with the same name has no <injection-target> elements. The Servlet 3.1 specification clarifies that for a resource reference of the same name, all <injection-target> elements in web-fragment.xml descriptors are added to the parent web.xml descriptors list of <injection-target> elements. The Servlet 3.1 feature might change existing application behavior by activating injection targets that were previously excluded from the web.xml file.

This rule flags the <injection-target> element in the web-fragment.xml file if the web.xml file contains an <injection-target> element within a <resource-ref> element that is defined with the same name as the <resource-ref> element in the web-fragment.xml file.

The following examples demonstrate the behavior change when you use a combination of a web.xml file and a web-fragment.xml file:

web.xml: 

<resource-ref>
	<res-ref-name>ReferenceName</res-ref-name>
	<res-type>javax.sql.DataSource</res-type>
	<res-auth>Container</res-auth>
	<res-sharing-scope>Shareable</res-sharing-scope>
	<injection-target>
		<injection-target-class>Class1</injection-target-class>
		<injection-target-name>Resource1</injection-target-name>
	</injection-target>
</resource-ref>

web-fragment.xml: 

<resource-ref>
	<res-ref-name>ReferenceName</res-ref-name>
	<res-type>javax.sql.DataSource</res-type>
	<res-auth>Container</res-auth>
	<res-sharing-scope>Shareable</res-sharing-scope>
	<injection-target>
		<injection-target-class>Class2</injection-target-class>
		<injection-target-name>Resource2</injection-target-name>
	</injection-target>
</resource-ref>

In Servlet 3.0 the combined result ignores the injection target for Class2: 

<resource-ref>
	<res-ref-name>ReferenceName</res-ref-name>
	<res-type>javax.sql.DataSource</res-type>
	<res-auth>Container</res-auth>
	<res-sharing-scope>Shareable</res-sharing-scope>
	<injection-target>
		<injection-target-class>Class1</injection-target-class>
		<injection-target-name>Resource1</injection-target-name>
	</injection-target>
</resource-ref>

In Servlet 3.1 the combined result uses the injection target for Class2: 

<resource-ref>
	<res-ref-name>ReferenceName</res-ref-name>
	<res-type>javax.sql.DataSource</res-type>
	<res-auth>Container</res-auth>
	<res-sharing-scope>Shareable</res-sharing-scope>
	<injection-target>
		<injection-target-class>Class1</injection-target-class>
		<injection-target-name>Resource1</injection-target-name>
	</injection-target>
	<injection-target>
		<injection-target-class>Class2</injection-target-class>
		<injection-target-name>Resource2</injection-target-name>
	</injection-target>
</resource-ref>

For more information on Servlet 3.1 behavior changes, see the following resource: Servlet 3.1 behavior changes.