error: incompatible types: NonExistentClass cannot be converted to Annotation @error.NonExistentClass()

Question

I am trying to generate Doka docs of my project. While generating I am getting an error like above. I have searched so many but could not able to get solution to this. I have gone through this link also. Here it is saying it might be a dagger related issue. I have tried these all solution also but not worked for me. I am posting here my all Gradle files for more clarification. if any one faced this issue or know the way to solve Please do comments.

Project Gradle :

 buildscript {
        ext.kotlin_version = '1.3.20'
        ext.dokkaVersion = '0.9.17'
        repositories {
            google()
            jcenter()
        }
        dependencies {
            classpath 'com.android.tools.build:gradle:3.3.1'
            classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
            classpath "org.jetbrains.dokka:dokka-android-gradle-plugin:$dokkaVersion"
            classpath "org.jetbrains.kotlin:kotlin-allopen:1.3.20"

            // NOTE: Do not place your application dependencies here; they belong
            // in the individual module build.gradle files
        }
    }

    allprojects {
        repositories {
            google()
            jcenter()
        }
    }

    task clean(type: Delete) {
        delete rootProject.buildDir
    }

App Gradle :

    apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

apply plugin: 'kotlin-kapt'
apply plugin: 'org.jetbrains.dokka-android'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.xx.xxx.xxx"
        minSdkVersion 23
        multiDexEnabled true
        targetSdkVersion 28
        versionCode 1
        versionName "1.0.3"
        multiDexEnabled true
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    dokka {
        outputFormat = 'html'
        outputDirectory = "$buildDir/documentation"
    }

    dataBinding {
        enabled = true
    }

    signingConfigs {
        platform {
            storeFile file("../certs/platform.keystore")
            storePassword 'xxxxxxxx'
            keyAlias 'platform'
            keyPassword 'xxxxxxxx'
        }
    }

    buildTypes {
        release {
            signingConfig signingConfigs.platform
            zipAlignEnabled true
        }
        debug {
            debuggable true
            signingConfig signingConfigs.platform
            zipAlignEnabled true
            testCoverageEnabled = true
        }
    }

    androidExtensions {
        experimental = true
    }

}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.0.0-alpha1'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0-alpha1'
    implementation 'com.android.support:support-v4:28.0.0'
    implementation 'com.android.support:appcompat-v7:28.0.0'
    testImplementation 'junit:junit:4.12'
    implementation 'com.android.support:multidex:1.0.3'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    implementation project(':library')
    implementation 'com.android.support:design:28.0.0'
    implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
    annotationProcessor 'com.google.dagger:dagger-compiler:2.21'
    annotationProcessor 'com.google.dagger:dagger-android-processor:2.21'
    implementation 'com.google.dagger:dagger:2.21'
    implementation 'com.google.dagger:dagger-android:2.21'
    implementation 'com.google.dagger:dagger-android-support:2.21'
    kapt 'com.google.dagger:dagger-compiler:2.21'
    kapt 'com.google.dagger:dagger-android-processor:2.21'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1-alpha3'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    implementation 'com.android.support.test:rules:1.0.2'
    implementation 'com.google.code.findbugs:jsr305:2.0.1'

library gradle :

    apply plugin: 'com.android.library'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
apply plugin: "kotlin-allopen"
apply from: '../buildsystem/android_commons.gradle'

allOpen {
    annotation 'com.xx.xxxx.xxxx.xxxxx'
}
android {

    defaultConfig {
        versionName "1.0"
        buildConfigField "String", "xx", "\"xx\""
    }

    androidExtensions {
        experimental = true
    }

}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'androidx.appcompat:appcompat:1.0.0-alpha1'
    testImplementation 'junit:junit:4.12'
    testImplementation 'org.mockito:mockito-core:1.10.19'
    androidTestImplementation 'androidx.test:runner:1.1.0-alpha3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha3'
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.google.dagger:dagger:2.21'
    implementation 'com.google.dagger:dagger-android:2.21'
    implementation 'com.google.dagger:dagger-android-support:2.21'
    kapt 'com.google.dagger:dagger-compiler:2.21'
    kapt 'com.google.dagger:dagger-android-processor:2.21'
    annotationProcessor 'com.google.dagger:dagger-compiler:2.21'
    annotationProcessor 'com.google.dagger:dagger-android-processor:2.21'
    implementation 'com.google.guava:guava:23.3-android'

}

repositories {
    mavenCentral()
}

Error:- Task :library:kaptReleaseKotlin FAILED error: incompatible types: NonExistentClass cannot be converted to Annotation @error.NonExistentClass()