Harmless but annoying warning with NativeBillingTransaction.cs

I'm getting this (harmless but annoying) warning after every recompile:

Assets/Plugins/VoxelBusters/EssentialKit/Runtime/Android/BillingServices/NativeBillingTransaction.cs(59,23): warning CS0114: 'NativeBillingTransaction.ToString()' hides inherited member 'object.ToString()'. To make the current member override that implementation, add the override keyword. Otherwise add the new keyword.