GP-145 Minor fixes

* update put method javadoc
* update a test for toString method

Author: tboychuk

2-0-data-structures-and-algorithms/2-2-7-hash-table/src/main/java/com/bobocode/cs/HashTable.java

@@ -47,13 +47,18 @@ public static int calculateIndex(Object key, int tableCapacity) {
     }
 
     /**
-     * Adds an element to the hash table. Does not support duplicate elements.
+     * Creates a mapping between provided key and value, and returns the old value. If there was no such key, it returns
+     * null. {@link HashTable} does not support duplicate keys, so if you put the same key it just overrides the value.
+     * <p>
+     * It uses calculateIndex method to find the corresponding array index. Please note, that even different keys can
+     * produce the same array index.
      *
-     * @param element
-     * @return true if it was added
+     * @param key
+     * @param value
+     * @return old value or null
      */
     @Override
-    public V put(K element, V value) {
+    public V put(K key, V value) {
         throw new ExerciseNotCompletedException(); // todo:
     }
 

2-0-data-structures-and-algorithms/2-2-7-hash-table/src/test/java/com/bobocode/cs/HashTableTest.java

@@ -470,7 +470,7 @@ void toStringTest() {
 
             String tableStr = hashTable.toString();
 
-            assertThat(expectedString).isEqualTo(tableStr);
+            assertThat(tableStr).isEqualTo(expectedString);
         }
 
     }