Attach information to ContactExistsException.

bramble-api/src/main/java/org/briarproject/bramble/api/db/ContactExistsException.java

@@ -1,8 +1,27 @@
 package org.briarproject.bramble.api.db;
 
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorId;
+
 /**
  * Thrown when a duplicate contact is added to the database. This exception may
  * occur due to concurrent updates and does not indicate a database error.
  */
 public class ContactExistsException extends DbException {
+
+	private final AuthorId local;
+	private final Author remote;
+
+	public ContactExistsException(AuthorId local, Author remote) {
+		this.local = local;
+		this.remote = remote;
+	}
+
+	public AuthorId getLocalAuthorId() {
+		return local;
+	}
+
+	public Author getRemoteAuthor() {
+		return remote;
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactExchangeManagerImpl.java

@@ -229,7 +229,7 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 			logException(LOG, WARNING, e);
 			tryToClose(conn);
 			eventBus.broadcast(
-					new ContactExchangeFailedEvent(remoteInfo.author));
+					new ContactExchangeFailedEvent(e.getRemoteAuthor()));
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
 			tryToClose(conn);

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -234,16 +234,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public ContactId addContact(Transaction transaction, Author remote,
-			AuthorId local, boolean verified)
+			AuthorId local, boolean verified) throws DbException {
-			throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsIdentity(txn, local))
 			throw new NoSuchIdentityException();
 		if (db.containsIdentity(txn, remote.getId()))
-			throw new ContactExistsException();
+			throw new ContactExistsException(local, remote);
 		if (db.containsContact(txn, remote.getId(), local))
-			throw new ContactExistsException();
+			throw new ContactExistsException(local, remote);
 		ContactId c = db.addContact(txn, remote, local, verified);
 		transaction.attach(new ContactAddedEvent(c));
 		return c;

bramble-core/src/test/java/org/briarproject/bramble/db/DatabaseComponentImplTest.java

@@ -1459,7 +1459,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 							true));
 			fail();
 		} catch (ContactExistsException expected) {
-			// Expected
+			assertEquals(localAuthor.getId(), expected.getLocalAuthorId());
+			assertEquals(author, expected.getRemoteAuthor());
 		}
 	}
 
@@ -1488,7 +1489,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 							true));
 			fail();
 		} catch (ContactExistsException expected) {
-			// Expected
+			assertEquals(localAuthor.getId(), expected.getLocalAuthorId());
+			assertEquals(author, expected.getRemoteAuthor());
 		}
 	}