Add javadocs.

bramble-api/src/main/java/org/briarproject/bramble/api/account/AccountManager.java

@@ -8,18 +8,58 @@ import javax.annotation.Nullable;
 @NotNullByDefault
 public interface AccountManager {
 
+	/**
+	 * Returns true if the manager has the database key. This will be false
+	 * before {@link #createAccount(String)} or {@link #signIn(String)} has
+	 * been called, and true after {@link #createAccount(String)} or
+	 * {@link #signIn(String)} has returned, until the process exits.
+	 */
 	boolean hasDatabaseKey();
 
+	/**
+	 * Returns the database key if the manager has it. This will be null
+	 * before {@link #createAccount(String)} or {@link #signIn(String)} has
+	 * been called, and non-null after {@link #createAccount(String)} or
+	 * {@link #signIn(String)} has returned, until the process exits.
+	 */
 	@Nullable
 	SecretKey getDatabaseKey();
 
+	/**
+	 * Returns true if the encrypted database key can be loaded from disk and
+	 * the database directory exists.
+	 */
 	boolean accountExists();
 
+	/**
+	 * Creates a database key, encrypts it with the given password and stores
+	 * it on disk. This method does not create the database directory, so
+	 * {@link #accountExists()} will continue to return false until the
+	 * database directory is created.
+	 */
 	boolean createAccount(String password);
 
+	/**
+	 * Deletes all account state from disk. {@link #accountExists()} will
+	 * return false after this method returns.
+	 */
 	void deleteAccount();
 
+	/**
+	 * Loads the encrypted database key from disk and decrypts it with the
+	 * given password.
+	 *
+	 * @return true if the database key was successfully loaded and decrypted.
+	 */
 	boolean signIn(String password);
 
+	/**
+	 * Loads the encrypted database key from disk, decrypts it with the old
+	 * password, encrypts it with the new password, and stores it on disk,
+	 * replacing the old key.
+	 *
+	 * @return true if the database key was successfully loaded, re-encrypted
+	 * and stored.
+	 */
 	boolean changePassword(String oldPassword, String newPassword);
 }