In the ColumnActionFactory, The given methods [addButton() and add()] conntains the direct String constants values ["bottom" and "add-circle-o"] but those could be defined in the UIConstants.

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 public HTMLElement addButton(String title, String iconCss)

{         return span().css(iconCss)                 .title(title)                 .data(UIConstants.TOGGLE, UIConstants.TOOLTIP)                 .data(UIConstants.PLACEMENT, "bottom").element();     }

public <T> ColumnAction<T> add(String id, String type, AddressTemplate template, ColumnActionHandler<T> handler)

{         return add(id, type, template, pfIcon("add-circle-o"), handler);     }

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Adding String constants to the 'UIConstants' and using in 'ColumnActionFactory'.

[String constants]:

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String  ADD_CIRCLE_O = "add-circle-o";

String BOTTOM = "bottom";

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