Espresso error signature


I have problems using Espresso within my customer app. I think that the problem comes because of the ‘io.appium.espressoserver.test’ package isn´t signed by the client. The Appium error is:

WebDriverException: Message: An unknown server-side error occurred while processing the command. Original error: java.lang.SecurityException: Permission Denial: starting instrumentationComponentInfo{io.appium.espressoserver.test/androidx.test.runner.AndroidJUnitRunner} from pid=29433, uid=29433 not allowed because package io.appium.espressoserver.test does not have a signature matching the target

My question is if i have to sign the espresso package and if the answer is yes, how could I do it? I tried to recompile the espresso package (clonning this ) with Android Studio and gradle but the result is a light apk (about 7KB). The client signed it and recompiled too with the same result, and when we tried to use Appium, it shows the same error.

Which is the correct file that we need to sustitute in the espresso folder? And, is there any flag or desired capability to avoid recompile the espresso apk?

Thanks everyone.