issue #335 review changes

monad/src/main/java/com/iluwatar/monad/App.java

@@ -1,7 +1,23 @@
 package com.iluwatar.monad;
 
 import java.util.Objects;
+import java.util.function.Function;
+import java.util.function.Predicate;
 
+/**
+ * The Monad pattern defines a monad structure, that enables chaining operations
+ * in pipelines and processing data step by step.
+ * Formally, monad consists of a type constructor M and two operations:
+ * <br>bind - that takes monadic object and a function from plain object to the
+ * monadic value and returns monadic value.
+ * <br>return - that takes plain type object and returns this object wrapped in a monadic value.
+ * <p>
+ * In the given example, the Monad pattern is represented as a {@link Validator} that takes an instance
+ * of a plain object with {@link Validator#of(Object)}
+ * and validates it {@link Validator#validate(Function, Predicate, String)} against given predicates.
+ * <p>As a validation result {@link Validator#get()} it either returns valid object {@link Validator#t}
+ * or throws a list of exceptions {@link Validator#exceptions} collected during validation.
+ */
 public class App {
 
   /**