I have a problem running my CI builds on Travis with Java9 (Oracle JDK 9).
I fails on maven-site-plugin - after removing it everything works smothly.
I tried removing everything else to check for possible dependencies collisions, left out with just this one plugin build still fails. It is just a pom container, still failing with just a simple site plugin (updated to latest version that claimed to be java9 ready).
Here are all of the resources:
Looking for similar problems on the web I found that usually it's plugin compatibility (all of the plugins ware updated) or different dependencies versions, but I removed all of them and it still fails.
The builds run locally on OpenJDK 9 perfectly fine.
-edit-
After applying hint from @nullpointer :
You should probably wait and update to using version 3.7 of site plugin as mentioned here.
Seems like you are encountering something similar to #MSITE-796
Quoting further from the same link:-
The release will need a little bit more time due to pending
SNAPSHOT-dependencies which need to be released first. So either have a little bit more patience or adddoxia-sitetools1.7.5as a dependency to the maven-site-plugin in your own project.
<dependency>
    <groupId>org.apache.maven.doxia</groupId>
    <artifactId>doxia-sitetools</artifactId>
    <version>1.7.5</version>
</dependency>
-edit-
As doxia-sitetools is just a pom container project one needs to update all of it's modules directly:
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-site-plugin</artifactId>
                <version>3.6</version>
                <dependencies>
                    <dependency>
                        <groupId>org.apache.maven.doxia</groupId>
                        <artifactId>doxia-decoration-model</artifactId>
                        <version>1.7.5</version>
                    </dependency>
                    <dependency>
                        <groupId>org.apache.maven.doxia</groupId>
                        <artifactId>doxia-skin-model</artifactId>
                        <version>1.7.5</version>
                    </dependency>
                    <dependency>
                        <groupId>org.apache.maven.doxia</groupId>
                        <artifactId>doxia-integration-tools</artifactId>
                        <version>1.7.5</version>
                    </dependency>
                    <dependency>
                        <groupId>org.apache.maven.doxia</groupId>
                        <artifactId>doxia-site-renderer</artifactId>
                        <version>1.7.5</version>
                    </dependency>
                    <dependency>
                        <groupId>org.apache.maven.doxia</groupId>
                        <artifactId>doxia-doc-renderer</artifactId>
                        <version>1.7.5</version>
                    </dependency>
                </dependencies>
            </plugin>
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