Fetch and store mailbox's supported api versions when pairing

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxProperties.java

@@ -2,6 +2,8 @@ package org.briarproject.bramble.api.mailbox;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+import java.util.List;
+
 import javax.annotation.concurrent.Immutable;
 
 @Immutable
@@ -11,12 +13,14 @@ public class MailboxProperties {
 	private final String baseUrl;
 	private final MailboxAuthToken authToken;
 	private final boolean owner;
+	private final List<MailboxVersion> serverSupports;
 
 	public MailboxProperties(String baseUrl, MailboxAuthToken authToken,
-			boolean owner) {
+			boolean owner, List<MailboxVersion> serverSupports) {
 		this.baseUrl = baseUrl;
 		this.authToken = authToken;
 		this.owner = owner;
+		this.serverSupports = serverSupports;
 	}
 
 	public String getBaseUrl() {
@@ -35,4 +39,8 @@ public class MailboxProperties {
 	public boolean isOwner() {
 		return owner;
 	}
+
+	public List<MailboxVersion> getServerSupports() {
+		return serverSupports;
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxVersion.java

@@ -0,0 +1,44 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class MailboxVersion implements Comparable<MailboxVersion> {
+
+	private final int major;
+	private final int minor;
+
+	public MailboxVersion(int major, int minor) {
+		this.major = major;
+		this.minor = minor;
+	}
+
+	public int getMajor() {
+		return major;
+	}
+
+	public int getMinor() {
+		return minor;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (o instanceof MailboxVersion) {
+			MailboxVersion v = (MailboxVersion) o;
+			return major == v.major && minor == v.minor;
+		}
+		return false;
+	}
+
+	@Override
+	public int compareTo(MailboxVersion v) {
+		int c = major - v.major;
+		if (c != 0) {
+			return c;
+		}
+		return minor - v.minor;
+	}
+}