Fix compiler warnings

The legacy code produced a number of compiler warnings when building,
which might distract from actual issues being introduced.

Enable all recommended warnings when building and address all compiler
warnings, mostly with a real fix, and suppress warnings in select cases
where a fix is not feasible, so that the library compiles without any
warnings.

Author: robert-s-ubi

build.gradle

@@ -23,6 +23,14 @@ subprojects {
     apply plugin: 'maven-publish'
     apply plugin: "com.github.sherter.google-java-format"
 
+    compileJava {
+        options.compilerArgs << '-Xlint:all'
+    }
+
+    compileTestJava {
+        options.compilerArgs << '-Xlint:all'
+    }
+
     repositories {
         mavenLocal()
         maven {

ocpp-common/src/main/java/eu/chargetime/ocpp/CallErrorException.java

@@ -27,6 +27,7 @@ of this software and associated documentation files (the "Software"), to deal
 
 /** Exception returned to an outgoing request if an error is reported from the other end. */
 public class CallErrorException extends Exception {
+  private static final long serialVersionUID = 2491636769263746241L;
 
   private String errorCode;
   private String errorDescription;

ocpp-common/src/main/java/eu/chargetime/ocpp/Communicator.java

@@ -27,6 +27,7 @@ of this software and associated documentation files (the "Software"), to deal
 SOFTWARE.
 */
 
+import eu.chargetime.ocpp.feature.Feature;
 import eu.chargetime.ocpp.model.*;
 import java.util.ArrayDeque;
 import org.slf4j.Logger;
@@ -54,6 +55,7 @@ public abstract class Communicator {
    * @param payload the raw formatted payload.
    * @param type the expected return type.
    * @return the unpacked payload.
+   * @param <T> the type of the unpacked payload.
    * @throws Exception error occurred while converting.
    */
   public abstract <T> T unpackPayload(Object payload, Class<T> type) throws Exception;
@@ -70,7 +72,7 @@ public abstract class Communicator {
    * Create a call result envelope to transmit.
    *
    * @param uniqueId the id the receiver expects.
-   * @param action action name of the feature.
+   * @param action action name of the {@link Feature}.
    * @param payload packed payload.
    * @return a fully packed message ready to send.
    */
@@ -80,7 +82,7 @@ public abstract class Communicator {
    * Create a call envelope to transmit to the server.
    *
    * @param uniqueId the id the receiver must reply with.
-   * @param action action name of the feature.
+   * @param action action name of the {@link Feature}.
    * @param payload packed payload.
    * @return a fully packed message ready to send.
    */
@@ -90,6 +92,7 @@ public abstract class Communicator {
    * Create a call error envelope to transmit.
    *
    * @param uniqueId the id the receiver expects.
+   * @param action action name of the {@link Feature}.
    * @param errorCode an OCPP error code.
    * @param errorDescription an associated error description.
    * @return a fully packed message ready to send.
@@ -101,6 +104,7 @@ protected abstract Object makeCallError(
    * Create a call result error envelope to transmit.
    *
    * @param uniqueId the id the receiver expects.
+   * @param action action name of the {@link Feature}.
    * @param errorCode an OCPP error code.
    * @param errorDescription an associated error description.
    * @return a fully packed message ready to send.
@@ -112,7 +116,7 @@ protected abstract Object makeCallResultError(
    * Create a send envelope to transmit to the server.
    *
    * @param uniqueId the id of the message.
-   * @param action action name of the feature.
+   * @param action action name of the {@link Feature}.
    * @param payload packed payload.
    * @return a fully packed message ready to send.
    */
@@ -177,7 +181,7 @@ public void accept(CommunicatorEvents events) {
    * Request}s.
    *
    * @param uniqueId the id the receiver should use to reply.
-   * @param action action name of the {@link eu.chargetime.ocpp.feature.Feature}.
+   * @param action action name of the {@link Feature}.
    * @param request the outgoing {@link Request}
    */
   public synchronized void sendCall(String uniqueId, String action, Request request) {
@@ -222,6 +226,7 @@ public synchronized void sendCall(String uniqueId, String action, Request reques
    * Send a {@link Confirmation} reply to a {@link Request}.
    *
    * @param uniqueId the id the receiver expects.
+   * @param action action name of the {@link Feature}.
    * @param confirmation the outgoing {@link Confirmation}
    */
   public void sendCallResult(String uniqueId, String action, Confirmation confirmation) {
@@ -255,7 +260,8 @@ public void sendCallResult(String uniqueId, String action, Confirmation confirma
    * Send an error. If offline, the message is thrown away.
    *
    * @param uniqueId the id the receiver expects a response to.
-   * @param errorCode an OCPP error Code
+   * @param action action name of the {@link Feature}.
+   * @param errorCode an OCPP error Code.
    * @param errorDescription a associated error description.
    */
   public void sendCallError(
@@ -282,7 +288,8 @@ public void sendCallError(
    * Send a call result error. If offline, the message is thrown away.
    *
    * @param uniqueId the id the receiver expects a response to.
-   * @param errorCode an OCPP error Code
+   * @param action action name of the {@link Feature}.
+   * @param errorCode an OCPP error Code.
    * @param errorDescription a associated error description.
    */
   public void sendCallResultError(
@@ -310,7 +317,7 @@ public void sendCallResultError(
    * Send a {@link Request} which has no confirmation.
    *
    * @param uniqueId the id of the {@link Request}.
-   * @param action action name of the {@link eu.chargetime.ocpp.feature.Feature}.
+   * @param action action name of the {@link Feature}.
    * @param request the outgoing {@link Request}
    */
   public synchronized void send(String uniqueId, String action, Request request) {

ocpp-common/src/main/java/eu/chargetime/ocpp/NotConnectedException.java

@@ -24,4 +24,6 @@ of this software and associated documentation files (the "Software"), to deal
                                SOFTWARE.
                             */
 
-public class NotConnectedException extends Exception {}
+public class NotConnectedException extends Exception {
+  private static final long serialVersionUID = -2192470845608175121L;
+}

ocpp-common/src/main/java/eu/chargetime/ocpp/OccurenceConstraintException.java

@@ -25,4 +25,6 @@ of this software and associated documentation files (the "Software"), to deal
                             */
 
 /** Exception thrown when trying to send a request that isn't valid. */
-public class OccurenceConstraintException extends Exception {}
+public class OccurenceConstraintException extends Exception {
+  private static final long serialVersionUID = -8870111792165582976L;
+}

ocpp-common/src/main/java/eu/chargetime/ocpp/PropertyConstraintException.java

@@ -28,7 +28,7 @@ of this software and associated documentation files (the "Software"), to deal
 
 /** Exception used when validating fields. */
 public class PropertyConstraintException extends IllegalArgumentException {
-
+  private static final long serialVersionUID = 7561578774874709893L;
   private static final String EXCEPTION_MESSAGE_TEMPLATE =
       "Validation failed: [%s]. Current Value: [%s]";
 

ocpp-common/src/main/java/eu/chargetime/ocpp/SecurityErrorException.java

@@ -29,6 +29,8 @@ of this software and associated documentation files (the "Software"), to deal
 
 /** A security issue occurred */
 public class SecurityErrorException extends IllegalStateException {
+  private static final long serialVersionUID = 630599636179474207L;
+
   public SecurityErrorException(String s) {
     super(s);
   }

ocpp-common/src/main/java/eu/chargetime/ocpp/Server.java

@@ -227,6 +227,7 @@ public void close() {
    * @throws UnsupportedFeatureException Thrown if the feature isn't among the list of supported
    *     features.
    * @throws OccurenceConstraintException Thrown if the request isn't valid.
+   * @throws NotConnectedException Thrown if session with passed sessionIndex is not found
    */
   public CompletableFuture<Confirmation> send(UUID sessionIndex, Request request)
       throws UnsupportedFeatureException, OccurenceConstraintException, NotConnectedException {
@@ -275,6 +276,9 @@ public CompletableFuture<Confirmation> send(UUID sessionIndex, Request request)
    * @param confirmation the {@link Confirmation} to the original {@link Request}.
    * @return a boolean indicating if pending request was found.
    * @throws NotConnectedException Thrown if session with passed sessionIndex is not found
+   * @throws UnsupportedFeatureException Thrown if the feature isn't among the list of supported
+   *     features.
+   * @throws OccurenceConstraintException Thrown if the request isn't valid.
    */
   public boolean asyncCompleteRequest(UUID sessionIndex, String uniqueId, Confirmation confirmation)
       throws NotConnectedException, UnsupportedFeatureException, OccurenceConstraintException {

ocpp-common/src/main/java/eu/chargetime/ocpp/Session.java

@@ -64,6 +64,8 @@ public class Session implements ISession {
    *
    * @param communicator send and receive messages.
    * @param queue store and restore requests based on unique ids.
+   * @param fulfiller the {@link PromiseFulfiller} to use
+   * @param featureRepository the {@link IFeatureRepository} to use
    */
   public Session(
       Communicator communicator,
@@ -150,6 +152,7 @@ public void removeRequest(String ticket) {
    * Send a {@link Confirmation} to a {@link Request}
    *
    * @param uniqueId the unique identification the receiver expects.
+   * @param action action name to identify the feature.
    * @param confirmation the {@link Confirmation} payload to send.
    */
   public void sendConfirmation(String uniqueId, String action, Confirmation confirmation) {

ocpp-common/src/main/java/eu/chargetime/ocpp/SessionEvents.java

@@ -47,6 +47,8 @@ public interface SessionEvents {
    *
    * @param request the {@link Request}.
    * @return a {@link Confirmation} to send as a response or {@code null} if none to send.
+   * @throws UnsupportedFeatureException Thrown if the feature isn't among the list of supported
+   *     features.
    */
   @Nullable
   Confirmation handleRequest(Request request) throws UnsupportedFeatureException;
@@ -57,6 +59,9 @@ public interface SessionEvents {
    * @param uniqueId the unique id used for the {@link Request}.
    * @param confirmation the {@link Confirmation} to the {@link Request}.
    * @return a boolean indicating if pending request was found.
+   * @throws UnsupportedFeatureException Thrown if the feature isn't among the list of supported
+   *     features.
+   * @throws OccurenceConstraintException Thrown if the request isn't valid.
    */
   boolean asyncCompleteRequest(String uniqueId, Confirmation confirmation)
       throws UnsupportedFeatureException, OccurenceConstraintException;