[ERROR] Failed to execute goal org.infinispan:infinispan-protocol-parser-generator-maven-plugin:9.4.6.Final-redhat-00001:generate (default) on project infinispan-server-hotrod: Execution default of goal org.infinispan:infinispan-protocol-parser-generator-maven-plugin:9.4.6.Final-redhat-00001:generate failed: character to be escaped is missing -> [Help 1]

The problem is most likely here:

File output = new File(outputDirectory, grammar.getPackage().replaceAll("\\.", File.separator) + File.separator + grammar.getSimpleName() + ".java");

On Windows, File.separator is \, and \ has a special meaning in the replaceAll replacement string.