There is an object (ObjectA) which has another object inside (ObjectB). There is a Guava TreeBasedTable inside the Object B. This Table has a string as row-key,column-key and another object "ObjectC" as value. This table has been displayed on the jsp using the <s:iterator/> and <s:textfield/> tags and it is being displayed correctly (the "values" inside the <s:textfield/> are correct but the "names" are not). 
Now, the problem arises when the <s:textfield/> is modified. How do we capture the modified values inside ObjectC in the action class?
public class ObjectA implements Serializable {
private Integer attr1;
private List<ObjectB> objB;
//...getters and setters....
public class ObjectB implements Serializable {
private Integer attr11;
private Table<String,String,ObjectC> allPFields;
// ...getters and setters....
public class ObjectC implements Serializable {
private Integer attr111;
public String attr112;
// ...getters and setters....
jsp code:
<!-- language: lang-html -->
<s:iterator value="#objB.allPlainFields.row(#rowKey)" var="fieldMap"
    status="fieldStatus">
    <li><label><s:property value="#fieldMap.key" /></label><span>
            <s:textfield name="<NOT SURE>" value="%{#fieldMap.value.attr12}" />
    </span></li>
</s:iterator>
A TreeBasedTable in Guava is similar to a map inside a map, I tried doing allPFields[#outerkey][#innerkey].attr112 but, it didn't work. 
The object structure when the screen is displayed with existing values in the database
<!-- language: lang-java -->
objA        
objBList    ArrayList<E>  (id=668)  
elementData Object[10]  (id=7438)   
    [0] objB  (id=7439) 
        allPFields  TreeBasedTable<R,C,V>  (id=7443)    
            backingMap  TreeMap<K,V>  (id=8116) 
            cellSet null    
            columnComparator    NaturalOrdering  (id=503)   
            columnKeySet    null    
            columnMap   null    
            factory TreeBasedTable$Factory<C,V>  (id=8117)  
            rowKeySet   null    
            rowKeySet   StandardRowSortedTable$RowKeySortedSet  (id=8118)   
            rowMap  StandardRowSortedTable$RowSortedMap  (id=8119)  
            rowMap  null    
            values  null
And the "allPFields" looks like the following in action:
{OuterKey1=
    {InnerKey1=ObjectC[attr111=31, attr112=Hi there], 
     InnerKey2=ObjectC[attr111=40, attr112=How are you]
    }
 }
The "allPFields" value above has been picked up from the IDE console.