<PackageReference Include="System.Collections.Immutable" Version="11.0.0-rc.3.26522.148" />

System.Collections.Frozen.KeyAnalyzer

static class KeyAnalyzer
namespace System.Collections.Frozen { internal static class KeyAnalyzer { private delegate ReadOnlySpan<char> GetSpan (string s, int index, int count); public static AnalysisResults Analyze(ReadOnlySpan<string> uniqueStrings, bool ignoreCase, int minLength, int maxLength); } }