How to enable Annotation Processor in Android Studio 2.3

Close the project and find the option under File -> Other Settings -> Default Settings -> Build, Execution, Deployment -> Compiler -> Annotation Processors

Exit from Android Studio and edit the file /.idea/compiler.xml.
You should find:

<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
    <component name="CompilerConfiguration">
        ...
        <annotationProcessing>
            <profile default="true" name="Default" enabled="false">
                <processorPath useClasspath="true" />
            </profile>
        </annotationProcessing>
    </component>
</project>

You should set enabled to true and the boring message disappears!

<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
    <component name="CompilerConfiguration">
        ...
        <annotationProcessing>
            <!-- This is the line where to set enabled to true  -->
            <profile default="true" name="Default" enabled="true">
                <processorPath useClasspath="true" />
            </profile>
        </annotationProcessing>
    </component>
</project>

References
https://stackoverflow.com/questions/42692525/how-to-enable-annotation-processor-in-android-studio-2-3

Related