Describe the bug
FileWriter doesn't seem to be thread safe. Android Gradle Plugin integrates with dokka-core and its javadoc plugin to generate javadoc for java/kotlin sources. In order to have more parallelism, we try to launch dokka via gradle workers so that there would more than one dokka generation tasks running at the same time. In this case, we notice test failures(flaky) from FileWriter complaining stream is closed when reading bytes.

see stacktrace

Caused by: java.io.IOException: Stream closed
	at kotlin.io.ByteStreamsKt.copyTo(IOStreams.kt:110)
	at kotlin.io.ByteStreamsKt.copyTo$default(IOStreams.kt:103)
	at kotlin.io.ByteStreamsKt.readBytes(IOStreams.kt:136)
	at org.jetbrains.dokka.base.renderers.FileWriter$copyFromJar$3.invokeSuspend(FileWriter.kt:74)
	at org.jetbrains.dokka.base.renderers.FileWriter$copyFromJar$3.invoke(FileWriter.kt)

I noticed dokka-gradle-plugin doesn't use gradle workers, which is also a sign that dokka-core doesn't is not thread safe.

Expected behaviour
FileWriter/Dokka-core to be thread safe.

Installation

• Operating system: Linux
• Build tool: Gradle 7.3.3 Android Gradle plugin 7.2.0-alpha07
• Dokka version: 1.4.30