Address review comments

Author: poojanilangekar

polaris-core/src/main/java/org/apache/polaris/core/secrets/UnsafeInMemorySecretsManager.java

@@ -43,7 +43,7 @@ public class UnsafeInMemorySecretsManager implements UserSecretsManager {
   private static final String CIPHERTEXT_HASH = "ciphertext-hash";
   private static final String ENCRYPTION_KEY = "encryption-key";
 
-  private static final String SECRET_MANAGER_TYPE = "unsafe-in-memory";
+  public static final String SECRET_MANAGER_TYPE = "unsafe-in-memory";
 
   /** {@inheritDoc} */
   @Override
@@ -74,9 +74,7 @@ public UserSecretReference writeSecret(
     String secretUrn;
     for (int secretOrdinal = 0; ; ++secretOrdinal) {
       String typeSpecificIdentifier = forEntity.getId() + ":" + secretOrdinal;
-      secretUrn =
-          UserSecretReferenceUrnHelper.buildUrn(SECRET_MANAGER_TYPE, typeSpecificIdentifier);
-
+      secretUrn = buildUrn(SECRET_MANAGER_TYPE, typeSpecificIdentifier);
       // Store the base64-encoded encrypted ciphertext in the simulated "secret store".
       String existingSecret =
           rawSecretStore.putIfAbsent(secretUrn, encryptedSecretCipherTextBase64);

polaris-core/src/main/java/org/apache/polaris/core/secrets/UserSecretsManager.java

@@ -63,4 +63,17 @@ public interface UserSecretsManager {
    * @param secretReference Reference object for retrieving the original secret
    */
   void deleteSecret(@Nonnull UserSecretReference secretReference);
+
+  /**
+   * Builds a URN string from the given secret manager type and type-specific identifier.
+   *
+   * @param typeSpecificIdentifier The type-specific identifier (colon-separated alphanumeric
+   *     components with underscores and hyphens).
+   * @return The constructed URN string.
+   */
+  @Nonnull
+  default String buildUrn(
+      @Nonnull String secretManagerType, @Nonnull String typeSpecificIdentifier) {
+    return UserSecretReferenceUrnHelper.buildUrn(secretManagerType, typeSpecificIdentifier);
+  }
 }