JaCoCo Code Coverage Under Default Element - How to Fix?

I'm using JaCoCo to measure unit test coverage in my Android project. While analyzing the report, I noticed that the code coverage for my classes is being grouped under the default package instead of their respective package names.

Here’s the coverage report screenshot: [

As you can see, the coverage for some classes is displayed under the default element. This causes confusion because it doesn't reflect the actual package structure of the project.

tasks.register("jacocoCoverage", JacocoReport) {
description = "Calculate code coverage using JaCoCo"
group = "verification"

dependsOn(tasks.named("testStageDebugUnitTest"))

executionData(fileTree(dir: "$buildDir", includes: ["**/*.exec"]))

sourceDirectories.setFrom(files(
        "$projectDir/src/main/java"
))

classDirectories.setFrom(fileTree(dir: "$buildDir/tmp/kotlin-classes", includes: [
        "stageDebugUnitTest/**/*.class"
]))

reports {
    xml.required.set(true)
    html.required.set(true)
    csv.required.set(false)
    html.outputLocation.set(file("$buildDir/jacoco/html"))
    xml.outputLocation.set(file("$buildDir/jacoco/jacoco.xml"))
}}

Why is JaCoCo grouping code coverage under default instead of their actual packages? How can I fix this issue so that the coverage report properly reflects the package structure?