I can't generate a class using Kotlin processor - kotlin

Question

I'm implementing a processor to generate kotlin code using custom annotations. The problem is that I cannot find a way to relate the annotation to the field it was declared for, and I cannot find a way to understand if a field is of a nullable type. The processor doesn't succeed to generate the code because the getAnnotationsByType doesn't return the annotations for the current field (the list it's empty). Not even the order is good, fields are passed first and the annotations after all the fields.
package it.kfi.xml.binding.processor
import com.google.auto.service.AutoService
import com.squareup.kotlinpoet.*
import it.kfi.xml.binding.annotations.XmlClass
import it.kfi.xml.binding.annotations.XmlProperty
import java.io.File
import java.lang.reflect.Type
import javax.annotation.Nullable
import javax.annotation.processing.AbstractProcessor
import javax.annotation.processing.Processor
import javax.annotation.processing.RoundEnvironment
import javax.lang.model.SourceVersion
import javax.lang.model.element.Element
import javax.lang.model.element.ElementKind
import javax.lang.model.element.TypeElement
import javax.lang.model.element.VariableElement
import javax.lang.model.type.NullType
import javax.lang.model.type.TypeMirror
import javax.print.DocFlavor
import javax.tools.Diagnostic
import kotlin.reflect.KClass
import kotlin.reflect.full.createType
#AutoService(Processor::class)
class XmlBinder : AbstractProcessor() {
companion object {
const val KAPT_KOTLIN_GENERATED_OPTION_NAME = "kapt.kotlin.generated"
}
override fun getSupportedAnnotationTypes(): MutableSet<String> {
return mutableSetOf(XmlClass::class.java.name)
}
override fun getSupportedSourceVersion(): SourceVersion = SourceVersion.latest()
override fun process(annotations: MutableSet<out TypeElement>?, roundEnv: RoundEnvironment): Boolean {
roundEnv.getElementsAnnotatedWith(XmlClass::class.java)
.forEach {
if (it.kind != ElementKind.CLASS) {
processingEnv.messager.printMessage(Diagnostic.Kind.ERROR, "Only classes can be annotated")
return true
}
processClass(it)
}
return false
}
private fun processClass(element: Element) {
val className = element.simpleName.toString() + "Model"
val packageName = processingEnv.elementUtils.getPackageOf(element).toString()
val classBuilder = TypeSpec.classBuilder(className)
classBuilder.addModifiers(KModifier.PUBLIC)
val initFromXml = FunSpec.builder("initFromXml")
initFromXml.addModifiers(KModifier.PUBLIC)
initFromXml.addParameter(ParameterSpec.builder("xml", String::class).build())
val properties = element.enclosedElements
var x: Int = 1
//Look for elements annotated with XmlField and add those elements to the generated class
for (property in properties) {
val annotation = property.getAnnotationsByType(XmlProperty::class.java)
val v = 10
classBuilder.addProperty(PropertySpec.varBuilder(property.simpleName.toString(), String::class, KModifier.PUBLIC).initializer(v.toString()).build())
initFromXml.addStatement("this.${property.simpleName} = \"${v.toString()}\"")
}
classBuilder.addFunction(initFromXml.build())
val fileName = "kfi_generated_$className"
val file = FileSpec.builder(packageName, fileName).addType(classBuilder.build()).build()
val kaptKotlinGeneratedDir = processingEnv.options[KAPT_KOTLIN_GENERATED_OPTION_NAME]
file.writeTo(File(kaptKotlinGeneratedDir))
}
}
Can anyone help me found a way to relate annotations to their fields or properties ?