I found a solution how to configure yGuard to exclude the one method in a class:
...
"rename"("logfile" to "${projectDir}/build/${rootProject.name}_renamelog.xml") {
"keep" {
"class"(
"name" to "my.x.y.ProcessUtil",
)
"method"(
"name" to "boolean doProcess()",
"class" to "my.x.y.ProcessUtil"
)
}
}
...