Why does every pom file published by Gradle has a self-referential dependency? - gradle

Question

When I try to convert a project from maven/sbt to Gradle:
https://github.com/tek/splain/blob/nexusRelease/Dev1/build.gradle.kts
I found a few problems, when comparing the new published pom file (by gradle):
...
<modelVersion>4.0.0</modelVersion>
<groupId>io.tryp</groupId>
<artifactId>splain_2.13.6</artifactId>
<version>1.0.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-compiler</artifactId>
<version>2.13.6</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>2.13.6</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>io.tryp</groupId>
<artifactId>splain_2.13.6</artifactId>
<version>1.0.0-SNAPSHOT</version>
<scope>compile</scope>
<optional>true</optional>
</dependency>
</dependencies>
</project>
with the old one (by sbt):
...
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-compiler</artifactId>
<version>2.13.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>2.13.5</version>
</dependency>
<dependency>
<groupId>com.chuusai</groupId>
<artifactId>shapeless_2.13</artifactId>
<version>2.3.3</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>dev.zio</groupId>
<artifactId>zio_2.13</artifactId>
<version>1.0.4</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.specs2</groupId>
<artifactId>specs2-core_2.13</artifactId>
<version>4.5.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
The pom file generated by gradle has a self-referential dependency to itself. This has caused nexus publishing to fail the sanity check. My questions are:
should this be illegal? Why is gradle permitting this?
why was it generated?
Gradle has a few other problems (like the deprecation of the provided scope) but so far this is the most serious of them all.

Answer 1

Fixed, turns out the problem was caused by "java-test-fixtures" plugin.
Test fixture doesn't have a maven scope counterpart, so by default their dependencies are merged into compile scope dependencies when publishing. The problem disappeared once I disabled their publishing:
val javaComponent = components["java"] as AdhocComponentWithVariants
from(javaComponent)
javaComponent.withVariantsFromConfiguration(configurations["testFixturesApiElements"]) { skip() }
javaComponent.withVariantsFromConfiguration(configurations["testFixturesRuntimeElements"]) { skip() }