Add for utf8 method in String/Utf8/Charsequence ListViews (#558)

* Adding add for utf8 and equals methods in String/Utf8/Charsequence ListViews

* removing unecessary equals method

* AddAll methods for List/Set

helper/helper/src/main/java/com/linkedin/avroutil1/compatibility/collectiontransformer/StringListView.java

@@ -38,16 +38,30 @@ public String set(int index, String element) {
     return previousValue;
   }
 
+  public String set(int index, Utf8 element) {
+    String previousValue = String.valueOf(_utf8List.get(index));
+    _utf8List.set(index, element);
+    return previousValue;
+  }
+
   @Override
   public void add(int index, String element) {
     _utf8List.add(index, new Utf8(element));
   }
 
+  public void add(int index, Utf8 element) {
+    _utf8List.add(index, element);
+  }
+
   @Override
   public boolean add(String element) {
     return _utf8List.add(new Utf8(element));
   }
 
+  public boolean add(Utf8 element) {
+    return _utf8List.add(element);
+  }
+
   @Override
   public boolean addAll(int index, java.util.Collection<? extends String> c) {
     boolean modified = false;
@@ -58,6 +72,30 @@ public boolean addAll(int index, java.util.Collection<? extends String> c) {
     return modified;
   }
 
+  /**
+   * Overloaded method to add all Utf8 elements of a collection at a specific index.
+   */
+  public boolean addAll(int index, java.util.List<? extends Utf8> c) {
+    boolean modified = false;
+    for (Utf8 element : c) {
+      _utf8List.add(index++, element);
+      modified = true;
+    }
+    return modified;
+  }
+
+  /**
+   * Overloaded method to add all Utf8 elements of a set at a specific index.
+   */
+  public boolean addAll(int index, java.util.Set<? extends Utf8> c) {
+    boolean modified = false;
+    for (Utf8 element : c) {
+      _utf8List.add(index++, element);
+      modified = true;
+    }
+    return modified;
+  }
+
   @Override
   public boolean remove(Object o) {
     return _utf8List.remove(new Utf8(o.toString()));