Add lint action for checkstyle

Reviewed-on: #1
Co-authored-by: Josh Chester <numbers@softwaresmyth.com>
Co-committed-by: Josh Chester <numbers@softwaresmyth.com>

src/main/java/com/softwaresmyth/functions/OrNot.java

@@ -2,18 +2,35 @@ package com.softwaresmyth.functions;
 
 import java.util.Optional;
 
-public class OrNot
+/**
+ * Utility class holding the library's methods.
+ */
+public enum OrNot
 {
+    ; // Enum with no variants for a utility class that is not meant to be instantiated.
+
+    /**
+     * Method that does nothing.
+     * It fits any method signature that returns void.
+     */
     public static void noop(Object... ignored)
     {
         //do nothing
     }
 
+    /**
+     * Method that does nothing.
+     * It fits any method signature that does not return void.
+     */
     public static <T> T returnNull(Object... ignored)
     {
         return null;
     }
 
+    /**
+     * Method that does nothing.
+     * It fits any method signature that returns {@link Optional} for any type.
+     */
     public static <T> Optional<T> returnEmpty(Object... ignored)
     {
         return Optional.empty();