core-android/src/main/java/com/uber/sdk/android/core/auth/AuthUtils.java
public static String customScopeCollectionToString(@NonNull Collection<String> scopes) {
        return TextUtils.join(" ", scopes).toLowerCase();
    }
public static String customScopeCollectionToString(@NonNull Collection<String> scopes) {
        return TextUtils.join(" ", scopes).toLowerCase();
    }
Converts a {@link Collection} of {@link String}s into a space-delimited {@link String}.

@param scopes the {@link Collection} of {@link String}s to convert
@return a space-delimited {@link String} of {@link Scope}s