<PackageReference Include="System.Security.Permissions" Version="11.0.0-preview.2.26159.112" />

System.Security.Policy.UnionCodeGroup

public sealed class UnionCodeGroup : CodeGroup
Represents a code group whose policy statement is the union of the current code group's policy statement and the policy statement of all its matching child code groups. This class cannot be inherited.
namespace System.Security.Policy { public sealed class UnionCodeGroup : CodeGroup { public UnionCodeGroup(IMembershipCondition membershipCondition, PolicyStatement policy); } }