[MSHADE-428] Typo causes mysterious NPE in build

[jira-importer]

Tamas Cservenak opened MSHADE-428 and commented

All versions are affected. 

Has this config for plugin:

<transformers>
  <transformer implementation="org.apache.maven.plugins.shade.resource.ComponentsXmlResourceTransformer" />
  <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer" />
  <transformer implementatioh="org.apache.maven.plugins.shade.resource.SisuIndexResourceTransformer" />
  <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
    <manifestEntries>
      <Main-Class>org.apache.maven.index.cli.NexusIndexerCli</Main-Class>
      <Multi-Release>true</Multi-Release>
    </manifestEntries>
  </transformer>
</transformers> 

And build was failing with 

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-shade-plugin:3.4.0:shade (default) on project indexer-cli: Error creating shaded jar: Problem shading JAR /home/cstamas/Worx/apache-maven/maven-indexer/indexer-cli/target/indexer-cli-7.0.0-SNAPSHOT.jar entry META-INF/sisu/javax.inject.Named: java.lang.NullPointerException -> [Help 1] 

Cause: there is a typo in config, notive implementatioH for sisu transformer.

This caused that list of transformes had a null element, and seems there is no validation that transformers list may not have null element. NPE happened when default shared method private boolean resourceTransformed( stepped onto null element and had null.canTransformResource( name ).

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Remote Links:

• GitHub Pull Request #229
  

[jira-importer]

Guillaume Nodet commented

It may be better to enhance maven so that a warning is issue in case an xml attribute / element can not be mapped during the mojo injection.

[jira-importer]

Tamas Cservenak commented

This is pure plexus that silently constructs an array of transformers that among themselves has null element and injects it here:

https://github.com/apache/maven-shade-plugin/blob/master/src/main/java/org/apache/maven/plugins/shade/mojo/ShadeMojo.java#L194

All shade mojo can do is to ensure that array has no null elements – and possibly fail if null element found.