make final

src/main/java/net/schmizz/sshj/connection/channel/ChannelOutputStream.java

@@ -54,7 +54,7 @@ public final class ChannelOutputStream
         implements ErrorNotifiable {
 
     private final Channel chan;
-    private Transport trans;
+    private final Transport trans;
     private final Window.Remote win;
     private final SSHPacket buffer = new SSHPacket();
     private final byte[] b = new byte[1];

src/main/java/net/schmizz/sshj/connection/channel/direct/SessionChannel.java

@@ -56,6 +56,8 @@ public class
         extends AbstractDirectChannel
         implements Session, Session.Command, Session.Shell, Session.Subsystem {
 
+    private final ChannelInputStream err = new ChannelInputStream(this, trans, lwin);
+
     private Integer exitStatus;
 
     private Signal exitSignal;
@@ -64,8 +66,6 @@ public class
 
     private Boolean canDoFlowControl;
 
-    private ChannelInputStream err = new ChannelInputStream(this, trans, lwin);
-
     public SessionChannel(Connection conn) {
         super(conn, "session");
     }

src/main/java/net/schmizz/sshj/signature/AbstractSignature.java

@@ -47,8 +47,8 @@ import java.security.SignatureException;
 public abstract class AbstractSignature
         implements Signature {
 
+    protected final String algorithm;
     protected java.security.Signature signature;
-    protected String algorithm;
 
     protected AbstractSignature(String algorithm) {
         this.algorithm = algorithm;

src/main/java/net/schmizz/sshj/userauth/method/KeyedAuthMethod.java

@@ -29,7 +29,8 @@ import java.security.PublicKey;
 
 public abstract class KeyedAuthMethod
         extends AbstractAuthMethod {
-    protected KeyProvider kProv;
+
+    protected final KeyProvider kProv;
 
     public KeyedAuthMethod(String name, KeyProvider kProv) {
         super(name);