Why do generic type restrictions have to be redeclared on descendant types?
interface IGenericType<T> where T : new()

class GenericTypeImplementation<U> : IGenericType<U>

class GenericTypeImplementation<U> : IGenericType<U> where U : new()

interface IGenericType<T> where T : new()
interface IGenericType2<T> where T : SomeOtherType
class GenericTypeImplementation<U> : IGenericType<U>, IGenericType2<U>
/* Hypothesis: Compiler can't infer U must be "SomeOtherType + new()" */

Error   1   The type 'U' must have a public parameterless constructor in order to use it as parameter 'T' in the generic type or method '....IGenericType<T>'
Error   2   The type 'U' must be convertible to '....SomeOtherType' in order to use it as parameter 'T' in the generic type or method '....IGenericType2<T>'

class GenericTypeImplementation<U> : IGenericType<U>, IGenericType2<U>
    where U : SomeOtherType, new()
{...}

class GenericTypeImplementation : IGenericType<SomeType>, IGenericType2<SomeOtherType>
{...}

class Implementation<T> : IGenericType<List<T>> { /* ... */ }

interface ISomething {
    void DoIt<T>() where T : new();
}

class OneThing : ISomething {
    public void DoIt<T>() where T : new() { }
}

class OtherThing : ISomething {
    void ISomething.DoIt<T>() { }
}