Resources plugin with cached-resources - grails

Question

Grails 2.3.7 and the cached resources plugin, at least with lesscss resources are not working properly.
The cached plugin returns an erro which is the same error as described in this thread:
<dt>Class</dt><dd>java.lang.NullPointerException</dd><dt>Message</dt><dd>Cannot invoke method cache() on null object</dd></dl><h2>Around line 31 of <span class="filename">grails-app/resourceMappers/org/grails/plugin/cachedresources/HashAndCacheResourceMapper.groovy</span></h2>
<pre class="snippet"><code class="line"><span class="lineNumber">28:</span> if (log.debugEnabled) {</code><code class="line"><span class="lineNumber">29:</span> log.debug "Setting caching headers on ${req.requestURI
http://grails.1312388.n4.nabble.com/Grails-resources-bug-Unable-to-load-resources-at-startup-td4652307.html
The problem is that cacheHeadersService is not injected or null in the cacheheaders plugin.
Trying to solve this I copied the contents of the cached-resources-plugin 1.1 from target/work/plugins to a local folder and added the following line:
grails.plugin.location.'cached-resources' = "../grailsplugins/cached-resources-1.1"
The intention was to fix this bug myself.
However, strangely enough, when the plugin is locally used the problem with injecting the cacheHeadersService is gone!
How can the plugin act differently when used locally versus when installed normally?
Perhaps it is a loader issue where now the cache-resources-plugin is loaded after whatever is declaring the service, but nonetheless worth reporting.
In the dependencies.groovy in the cache-resources plugin it declares the dependency:
compile ":cache-headers:1.0.4"
but obviosuly it is not loaded before the plugin unless loaded from local directory, strange!
I am also wondering, since the cache-resources plugin declares a dependency on tomcat :
build(":tomcat:$grailsVersion",
":release:2.0.3",
":rest-client-builder:1.0.2") {
export = false
}
is tomcat a requirement? Trying to change to Jetty in the main application the build process fails, saying that tomcat can not be found in the repository.
build ":jetty:2.0.3"// ":tomcat:7.0.52.1"
I just found these similar questions as well:
Cached-resources plugin is not working?
Grails Cache resources not working
Resource not found on grails appliction with cache plugins