System.Action<T1, T2, T3, T4, T5>

public sealed delegate Action<T1, T2, T3, T4, T5> : MulticastDelegate

namespace System { public delegate void Action<in T1, in T2, in T3, in T4, in T5> (T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5); }