Java driver VST Keep-Alive configuration (#595)

Author: rashtao

3.4/drivers/java-reference-setup.md

@@ -203,3 +203,23 @@ Connection TTL can be disabled setting it to `null`:
 ```
 
 The default TTL is `null` (no automatic connection closure).
+
+
+## VST Keep-Alive
+
+Since version 6.8 the driver supports setting keep-alive interval (in seconds)
+for VST connections. If set, every VST connection will perform a no-op request
+at the specified intervals, to avoid to be closed due to inactivity by the
+server (or by the external environment, e.g. firewall, intermediate routers,
+operating system, ... ).
+
+This option can be set using the key `arangodb.connections.keepAlive.interval`
+in the properties file or programmatically from the driver builder:
+
+```Java
+ArangoDB arangoDB = new ArangoDB.Builder()
+  .keepAliveInterval(1800) // 30 minutes
+  .build();
+```
+
+If not set or set to `null` (default), no keep-alive probes will be sent.

3.7/drivers/java-reference-setup.md

@@ -216,3 +216,23 @@ Connection TTL can be disabled setting it to `null`:
 ```
 
 The default TTL is `null` (no automatic connection closure).
+
+
+## VST Keep-Alive
+
+Since version 6.8 the driver supports setting keep-alive interval (in seconds)
+for VST connections. If set, every VST connection will perform a no-op request
+at the specified intervals, to avoid to be closed due to inactivity by the
+server (or by the external environment, e.g. firewall, intermediate routers,
+operating system, ... ).
+
+This option can be set using the key `arangodb.connections.keepAlive.interval`
+in the properties file or programmatically from the driver builder:
+
+```Java
+ArangoDB arangoDB = new ArangoDB.Builder()
+  .keepAliveInterval(1800) // 30 minutes
+  .build();
+```
+
+If not set or set to `null` (default), no keep-alive probes will be sent.