```abstract class MemoryCache<T> { private val cachedValue = AtomicReference<T>() ...

# detekt

[Eugen Martynov]

abstract class MemoryCache<T> {

    private val cachedValue = AtomicReference<T>()

    fun getOrEmpty(): Maybe<T> = Maybe.fromCallable { cachedValue.get() }

    fun set(value: T) {
        this.cachedValue.set(value)
    }

    fun invalidate() {
        cachedValue.set(null)
    }
}

This class has concrete methods

[Mike]

In this case, it's referring to the second recommendation.

Abstract classes which do not define any abstract members should instead be refactored into concrete classes.

[Mike]

If you made it abstract because you don't want it instantiated directly, but it is used as a parent class, then add an @Suppress("UnnecessaryAbstractClass") to the class, and Detekt will not report that issue.

[Eugen Martynov]

It is exactly abstract because I don’t want to instantiate it

[Eugen Martynov]

thanks

[Eugen Martynov]

I probably will disable this rule at all

[yousefa2]

Why not use an interface with default implementations?

[Mike]

That's also a good suggestion. If you're on JDK8, don't forget to add the @JvmDefault annotation to it, too, so that the compiler will generated the bytecode.