Unable to use reference contributor on custom language lexer token.

Hello,

I have been fiddling about with the custom language tutorial for a few days, and the tutorial is quite well made, up to the confusing JAVA-Simple language interop.

I am trying to resolve references from inside template strings

The syntax highlighting with the annotator works well, i have configured the full declaration to use the extension point (it was tricky to find how btw). It even runs the function:

override fun registerReferenceProviders(registrar: PsiReferenceRegistrar) {
    println("init")
    registrar.registerReferenceProvider(PlatformPatterns.psiElement(ArtusNamedElement::class.java), ReferenceProvider())
}

class ReferenceProvider : PsiReferenceProvider() {

    override fun getReferencesByElement(element: PsiElement, ctx: ProcessingContext): Array<PsiReference> {
        if (element is ArtusNativeFunctionDefinition) {
            val refs = mutableListOf<ArtusNativeVariableReference>()
            val params = element.functionParameters.functionParameterList.map { it.name_.text }
            element.node.getChildren(TokenSet.create(ArtusTypes.STRING)).forEach {
                val str = it.text
                val elem = it
                params.forEach {
                    var ind = str.indexOf("$" + it)
                    while (ind > 0) {
                        val i = ind + elem.startOffset - element.textOffset
                        println(i)
                        refs.add(ArtusNativeVariableReference(element, element, TextRange(i, i + it.length + 1)))
                        ind = str.indexOf("$" + it, ind + it.length + 1)
                    }
                }
            }
            return refs.toTypedArray()
        }
        return PsiReference.EMPTY_ARRAY
    }
}

some of the output in the console:

init
63
67
63
67
63
67
63
67
63
67
63
67
63
67
63
67
48
52
61

But inside the editor nothing shows up at all, i cannot go to declaration, or refactor as needed (the other classes are similarly implemented to the tutorial classes.

may be it is the 

ArtusNativeVariableReference

i use, here is the declaration:

class ArtusNativeVariableReference(val parent: ArtusNativeFunctionDefinition, element: PsiElement, textRange: TextRange): PsiReferenceBase<PsiElement>(element, textRange) {
    val name = element.text.substring(textRange.startOffset, textRange.endOffset)
    override fun resolve(): PsiElement? {
        return parent.functionParameters.functionParameterList.find { it.name_.text == name }?.name_
    }

    override fun getVariants(): Array<Any> {
        return parent.functionParameters.functionParameterList
                .map { LookupElementBuilder.create(it.name_).withIcon(ArtusIcons.FILE).withTypeText(it.containingFile.name) }
                .toTypedArray()
    }
}

but it does correctly return the values it should according to the documentation...

here is the bnf declaration of the construct, as you see getName and setName are implemented:

nativeFunctionDefinition ::= DOC? VOLATILE? 'native' '(' architectureDefinition ')' ('<' genericTypeDefinitions '>')? NAME_ '(' functionParameters ')' STRING+ {methods=[getName setName getNameElement getAbsolutePath getAvailableImports]}

plugin.xml for reference:

<idea-plugin>
    <id>com.artuslang.artuslang</id>
    <name>Artus Language Support</name>
    <version>1.0</version>
    <vendor email="support@artuslang.com" url="http://www.artuslang.com">Artus Systems</vendor>

    <description><![CDATA[
      Official Artus Language Support.<br>
    ]]></description>

    <change-notes><![CDATA[
      -/<br>
    ]]>
    </change-notes>

    <!-- please see http://www.jetbrains.org/intellij/sdk/docs/basics/getting_started/build_number_ranges.html for description -->
    <idea-version since-build="145.0"/>

    <!-- please see http://www.jetbrains.org/intellij/sdk/docs/basics/getting_started/plugin_compatibility.html
         on how to target different products -->
    <depends>com.intellij.modules.lang</depends>

    <extensions defaultExtensionNs="com.intellij">
        <fileTypeFactory implementation="com.artuslang.artuslang.ArtusFileTypeFactory"/>
        <lang.commenter language="Artus" implementationClass="com.artuslang.artuslang.lang.ArtusCommenter"/>
        <lang.parserDefinition language="Artus" implementationClass="com.artuslang.artuslang.lang.ArtusParserDefinition"/>
        <lang.syntaxHighlighterFactory language="Artus" implementationClass="com.artuslang.artuslang.syntax.ArtusSyntaxHighlighterFactory"/>
        <annotator language="Artus" implementationClass="com.artuslang.artuslang.annotator.ArtusAnnotator"/>
        <colorSettingsPage implementation="com.artuslang.artuslang.syntax.settings.ArtusColorSettingPage"/>
        <psi.referenceContributor language="Artus" implementation="com.artuslang.artuslang.reference.ArtusReferenceContributor"/>
        <lang.refactoringSupport language="Artus" implementationClass="com.artuslang.artuslang.refactoring.ArtusRefactoringSupportProvider"/>
        <!-- Add your extensions here -->
    </extensions>

    <actions>
        <!-- Add your actions here -->
    </actions>

</idea-plugin>

Any ideas what i am doing wrong?

A tutorial dedicated to fully a independent language plugin with full feature set would be most welcome on the tutorial page.