Fixed jakarta.faces.WEBAPP_CONTRACTS_DIRECTORY spec/impl mismatch

[BalusC]

Refactor retrieval and validation of webapp contracts directory into a single place and fixed a couple of misassumptions about it always being an absolute path.

#5329

[pizzi80]

path.isBlank()

[BalusC]

not part of fix, but indeed candidate to be improved project-wide in a new pr

[pizzi80]

just because you were editing those files ... ;)

[pizzi80]

path.isBlank()

[BalusC]

not part of fix, but indeed candidate to be improved project-wide in a new pr

[pizzi80]

just because you were editing those files ... ;)

[mnriem]

LGTM

[andresluuk]

Maybe this one broke some logic or there is something I must change on using ui:composition now because of the contract change?
We have a place similar to this tutorial:
https://javaee.github.io/tutorial/jsf-facelets008.html#:~:text=Resource%20library%20contracts%20allow%20you,section%20of%20your%20web%20application.
<ui:composition xmlns:ui="http://xmlns.jcp.org/jsf/facelets" template="/template.xhtml" />
with a

<faces-config>
    <application>
        <resource-library-contracts>
            <contract-mapping>
                <url-pattern>*</url-pattern>
                <contracts>default</contracts>
            </contract-mapping>
        </resource-library-contracts>
    </application>
</faces-config>

Now when I debug I see that template.xhtml is resolved into: file:/C:/../testContractMappings/webapp/contracts/default/template.xhtml which is correct.
but because isContractsResource is true, which is also correct for that, I will get "IOException: Contract resources cannot be accessed this way" from DefaultFacelet.

Caused by: jakarta.faces.view.facelets.TagAttributeException: /test.xhtml @2,96 <ui:composition template="template.xhtml"> Invalid path : template.xhtml
        at jakarta.faces.impl@4.0.5//com.sun.faces.facelets.tag.ui.CompositionHandler.apply(CompositionHandler.java:134)
        at jakarta.faces.impl@4.0.5//com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:52)
        at jakarta.faces.impl@4.0.5//com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:46)
        at jakarta.faces.impl@4.0.5//com.sun.faces.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:132)
        at jakarta.faces.impl@4.0.5//com.sun.faces.application.view.FaceletViewHandlingStrategy.buildView(FaceletViewHandlingStrategy.java:331)
        at jakarta.faces.impl@4.0.5//com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:70)
        at jakarta.faces.impl@4.0.5//com.sun.faces.lifecycle.Phase.doPhase(Phase.java:72)
        at jakarta.faces.impl@4.0.5//com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:150)
        at jakarta.faces.impl@4.0.5//jakarta.faces.webapp.FacesServlet.executeLifecyle(FacesServlet.java:692)
        ... 45 more
Caused by: java.io.IOException: Contract resources cannot be accessed this way
        at jakarta.faces.impl@4.0.5//com.sun.faces.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:298)
        at jakarta.faces.impl@4.0.5//com.sun.faces.facelets.impl.DefaultFaceletContext.includeFacelet(DefaultFaceletContext.java:154)
        at jakarta.faces.impl@4.0.5//com.sun.faces.facelets.tag.ui.CompositionHandler.apply(CompositionHandler.java:129)
        ... 53 more

Now after the change, can't ui:composition be used with contract-mapping-s any more or maybe I must change something in the mapping to get it working with contracts again? We have not set jakarta.faces.WEBAPP_CONTRACTS_DIRECTORY.