Drop the unused `Key` utility class

service/src/main/java/org/whispersystems/textsecuregcm/storage/Key.java

@@ -1,64 +0,0 @@
-/*
- * Copyright 2013-2020 Signal Messenger, LLC
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-package org.whispersystems.textsecuregcm.storage;
-
-import java.io.IOException;
-
-class Key {
-
-  private final byte[] userMessageQueue;
-  private final byte[] userMessageQueueMetadata;
-  private final byte[] userMessageQueuePersistInProgress;
-
-  private final String address;
-  private final long   deviceId;
-
-  Key(String address, long deviceId) {
-    this.address                           = address;
-    this.deviceId                          = deviceId;
-    this.userMessageQueue                  = ("user_queue::" + address + "::" + deviceId).getBytes();
-    this.userMessageQueueMetadata          = ("user_queue_metadata::" + address + "::" + deviceId).getBytes();
-    this.userMessageQueuePersistInProgress = ("user_queue_persisting::" + address + "::" + deviceId).getBytes();
-  }
-
-  String getAddress() {
-    return address;
-  }
-
-  long getDeviceId() {
-    return deviceId;
-  }
-
-  byte[] getUserMessageQueue() {
-    return userMessageQueue;
-  }
-
-  byte[] getUserMessageQueueMetadata() {
-    return userMessageQueueMetadata;
-  }
-
-  byte[] getUserMessageQueuePersistInProgress() {
-    return userMessageQueuePersistInProgress;
-  }
-
-  static byte[] getUserMessageQueueIndex() {
-    return "user_queue_index".getBytes();
-  }
-
-  static Key fromUserMessageQueue(byte[] userMessageQueue) throws IOException {
-    try {
-      String[] parts = new String(userMessageQueue).split("::");
-
-      if (parts.length != 3) {
-        throw new IOException("Malformed key: " + new String(userMessageQueue));
-      }
-
-      return new Key(parts[1], Long.parseLong(parts[2]));
-    } catch (NumberFormatException e) {
-      throw new IOException(e);
-    }
-  }
-}