Get MethodInfo of method - This operation is only valid on generic types

I have the following two Entity Framework's Include methods:

public static IIncludableQueryable<TEntity, TProperty> Include<TEntity, TProperty>(
    [NotNullAttribute] this IQueryable<TEntity> source, 
    [NotNullAttribute] Expression<Func<TEntity, TProperty>> navigationPropertyPath) 
    where TEntity : class;

public static IQueryable<TEntity> Include<TEntity>(
    [NotNullAttribute] this IQueryable<TEntity> source,
    [NotNullAttribute][NotParameterized] string navigationPropertyPath) 
    where TEntity : class;

I need to get the MethodInfo for both methods. For the first one I used:

  MethodInfo include1 = typeof(EntityFrameworkQueryableExtensions)
    .GetMethods().First(x => x.Name == "Include" && x.GetParameters()
    .Select(y => y.ParameterType.GetGenericTypeDefinition())
    .SequenceEqual(new[] { typeof(IQueryable<>), typeof(Expression<>) }));

This works but when I try to get the second one using the following:

  MethodInfo include2 = typeof(EntityFrameworkQueryableExtensions)
    .GetMethods().First(x => x.Name == "Include" && x.GetParameters()
    .Select(y => y.ParameterType.GetGenericTypeDefinition())
    .SequenceEqual(new[] { typeof(IQueryable<>), typeof(String) }));

I get the error:

This operation is only valid on generic types

What am I missing?