<PackageReference Include="System.Formats.Asn1" Version="11.0.0-preview.2.26159.112" />

System.StringPolyfills

static class StringPolyfills
Provides downlevel polyfills for string extension methods.
public static bool Contains(this string s, char value)

public static bool EndsWith(this string s, char value)

public static bool StartsWith(this string s, char value)