Install Oracle JDK 8 if doJFR requested.

See previous commit for context.

With OpenJDK 11 this won't hopefully
be no issue anymore.
(http://openjdk.java.net/jeps/328)

[Bug][Toolbox]

org.lamport.tla.toolbox.jclouds/src/org/lamport/tla/toolbox/jcloud/CloudDistributedTLCJob.java

@@ -278,21 +278,21 @@ public class CloudDistributedTLCJob extends Job {
 				// Send remote TLC's stdout to local stdout (this throws a TransportException
 				// unless shutdown is postponed by a few minutes above).
 				ByteStreams.copy(channel.getOutput(), System.out);
-//				if (doJfr) {
-//					// Get Java Flight Recording from remote machine and save if to a local file in
-//					// the current working directory. We call "cat" because sftclient#get fails with
-//					// the old net.schmizz.sshj and an update to the newer com.hierynomus seems 
-//					// awful lot of work.
-//					channel = sshClient.execChannel("cat /mnt/tlc/tlc.jfr");
-//					final InputStream output = channel.getOutput();
-//					final String cwd = Paths.get(".").toAbsolutePath().normalize().toString() + File.separator;
-//					final File jfr = new File(cwd + "tlc.jfr");
-//					ByteStreams.copy(output, new FileOutputStream(jfr));
-//					if (jfr.length() == 0) {
-//						System.err.println("Received empty Java Flight recording. Not creating tlc.jfr file");
-//						jfr.delete();
-//					}
-//				}
+				if (doJfr) {
+					// Get Java Flight Recording from remote machine and save if to a local file in
+					// the current working directory. We call "cat" because sftclient#get fails with
+					// the old net.schmizz.sshj and an update to the newer com.hierynomus seems 
+					// awful lot of work.
+					channel = sshClient.execChannel("cat /mnt/tlc/tlc.jfr");
+					final InputStream output = channel.getOutput();
+					final String cwd = Paths.get(".").toAbsolutePath().normalize().toString() + File.separator;
+					final File jfr = new File(cwd + "tlc.jfr");
+					ByteStreams.copy(output, new FileOutputStream(jfr));
+					if (jfr.length() == 0) {
+						System.err.println("Received empty Java Flight recording. Not creating tlc.jfr file");
+						jfr.delete();
+					}
+				}
 				// Finally close the ssh connection.
 				sshClient.disconnect();
 				monitor.subTask("TLC model checker process finished");
@@ -547,6 +547,8 @@ public class CloudDistributedTLCJob extends Job {
 							+ " && "
 							+ params.getHostnameSetup()
 							+ " && "
+							// Oracle Java 8
+							+ (doJfr ? "add-apt-repository ppa:webupd8team/java -y && " : "/bin/true && ")
 							// Accept license before apt (dpkg) tries to present it to us (which fails due to 'noninteractive' mode below)
 							// see http://stackoverflow.com/a/19391042
 							+ "echo debconf shared/accepted-oracle-license-v1-1 select true | sudo debconf-set-selections && "
@@ -594,6 +596,8 @@ public class CloudDistributedTLCJob extends Job {
 							+ "apt-get install --no-install-recommends mdadm e2fsprogs screen zip unattended-upgrades "
 									+ params.getExtraPackages() + " -y"
 							+ " && "
+							+ (doJfr ? "apt-get install --no-install-recommends oracle-java8-installer oracle-java8-set-default -y " : "/bin/true")
+							+ " && "
 							// Delegate file system tuning to cloud specific code.
 							+ params.getOSFilesystemTuning()
 							// Install Oracle Java8. It supports Java Mission