Matrix Authorization 3.0 has PermissionEntry class with methods:

1. public static PermissionEntry fromString(@NonNull String permissionEntryString);
2. public String toString();

Where 1 is suitable for reading from persisted storage.

Where 2 is suitable for marshaling into JSON.

Unseen is method for marshaling into persisted storage; may I suggest either:

• public String asString();
• public String intoString();

IMO adding proposed method here is superior to sub-classing PermissionEntry in Role-based Authorization.