The presence of this tag in a <composite:implementation> section must cause the named facet to be taken from the facet map of the top level component and inserted as a facet child of the component in which this element is nested. The results are undefined if there are facets in the composite component tag in the using page, but there is no correspondingly named occurrence of this element in the <composite:implementation> section.
javax.el.ValueExpression (must evaluate to java.lang.String)
The name of the facet child on the top level component which must be inserted as a facet child of the component in which this element is nested.
javax.el.ValueExpression (must evaluate to boolean)
If true, and there is no such facet present on the top level component, a TagException must be thrown, containing the Location, the facet name, and a localized descriptive error message.