Code-generator does not allow you to place *Ext.java classes in src/test/java

[Doug Simmons]

If a person want's to limit their {PageObject}Ext.java classes to the src/test/java (test) scope, the code generator will not consider them.

The code-generator plugin should allow for PageObject classes to be limited to 'test' only code.

CodeGeneratorMojo#sourceDir() is the root of the issue here.

[Doug Simmons]

fix merged with #287