l10n plugin is not threadsafe and builds occasionally fail if Maven threading is used

Can be reproduced by running mvn clean install -T1C.

Actual result: build fails when using Maven threading option. Maven prints warning that l10n plugin is not threadsafe

Expected result: build passes
[2019-12-13T00:46:27.786Z] [WARNING] The following plugins are not marked @threadSafe in OWASP dependency check CMS:[2019-12-13T00:46:27.786Z] [WARNING] org.onehippo.cms.l10n:hippo-cms-l10n-maven-plugin:14.1.0-SNAPSHOT
...
[2019-12-13T00:46:27.798Z] [ERROR] ConcurrentModificationException*01:46:27* java.util.ConcurrentModificationException*01:46:27* at java.util.LinkedHashMap$LinkedHashIterator.nextNode (LinkedHashMap.java:719)01:46:27 at java.util.LinkedHashMap$LinkedKeyIterator.next (LinkedHashMap.java:742)01:46:27 at org.apache.maven.project.DefaultProjectDependenciesResolver.resolve (DefaultProjectDependenciesResolver.java:136)01:46:27 at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.getDependencies (LifecycleDependencyResolver.java:243)01:46:27 at org.apache.maven.lifecycle.internal.LifecycleDependencyResolver.resolveProjectDependencies (LifecycleDependencyResolver.java:147)01:46:27 at org.apache.maven.lifecycle.internal.MojoExecutor.ensureDependenciesAreResolved (MojoExecutor.java:263)01:46:27 at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:200)01:46:27 at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)01:46:27 at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)01:46:27 at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)