Move most API of CommandParts to util classes

Gradual transition to removing CommandParts altogether.
 - Move logic from CommandParts to utils classes

src/test/java/fr/xephi/authme/command/executable/email/AddEmailCommandTest.java

@@ -11,6 +11,7 @@ import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 
 import static org.mockito.Mockito.never;
@@ -40,7 +41,7 @@ public class AddEmailCommandTest {
         AddEmailCommand command = new AddEmailCommand();
 
         // when
-        command.executeCommand(sender, new CommandParts(), new CommandParts());
+        command.executeCommand(sender, newParts(), newParts());
 
         // then
         verify(authMeMock, never()).getManagement();
@@ -53,11 +54,15 @@ public class AddEmailCommandTest {
         AddEmailCommand command = new AddEmailCommand();
 
         // when
-        command.executeCommand(sender, new CommandParts(),
+        command.executeCommand(sender, newParts(),
                 new CommandParts(Arrays.asList("mail@example", "other_example")));
 
         // then
         verify(authMeMock).getManagement();
         verify(managementMock).performAddEmail(sender, "mail@example", "other_example");
     }
+
+    private static CommandParts newParts() {
+        return new CommandParts(new ArrayList<String>());
+    }
 }

src/test/java/fr/xephi/authme/command/executable/email/ChangeEmailCommandTest.java

@@ -11,6 +11,7 @@ import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 
 import static org.mockito.Mockito.never;
@@ -40,7 +41,7 @@ public class ChangeEmailCommandTest {
         ChangeEmailCommand command = new ChangeEmailCommand();
 
         // when
-        command.executeCommand(sender, new CommandParts(), new CommandParts());
+        command.executeCommand(sender, newParts(), newParts());
 
         // then
         verify(authMeMock, never()).getManagement();
@@ -53,11 +54,15 @@ public class ChangeEmailCommandTest {
         ChangeEmailCommand command = new ChangeEmailCommand();
 
         // when
-        command.executeCommand(sender, new CommandParts(),
+        command.executeCommand(sender, newParts(),
                 new CommandParts(Arrays.asList("new.mail@example.org", "old_mail@example.org")));
 
         // then
         verify(authMeMock).getManagement();
         verify(managementMock).performChangeEmail(sender, "new.mail@example.org", "old_mail@example.org");
     }
+
+    private static CommandParts newParts() {
+        return new CommandParts(new ArrayList<String>());
+    }
 }

src/test/java/fr/xephi/authme/command/executable/email/RecoverEmailCommandTest.java

@@ -9,6 +9,8 @@ import org.junit.Ignore;
 import org.junit.Test;
 import org.mockito.Mockito;
 
+import java.util.Collections;
+
 /**
  * Test for {@link RecoverEmailCommand}.
  */
@@ -27,7 +29,7 @@ public class RecoverEmailCommandTest {
         RecoverEmailCommand command = new RecoverEmailCommand();
 
         // when
-        command.executeCommand(sender, new CommandParts(), new CommandParts());
+        command.executeCommand(sender, new CommandParts(Collections.EMPTY_LIST), new CommandParts(Collections.EMPTY_LIST));
 
         // then
     }