From where did Mary get the attribution of "Full of Grace"?

The Catholic prayer referred to as a "Hail Mary" ascribes the phrase "full of grace" to Mary. The Scriptures describe both Jesus and Stephen as being "full of grace". In Greek, this is "πλήρης χάριτος". > And the Word became flesh and dwelt among us, and we have seen his > glory, glory as of the only Son from the Father, **full of grace** and > truth. John 1:14 ESV > > And Stephen, full of grace and power, was doing great wonders and > signs among the people. Acts 6:8 ESV However, there doesn't seem to be any place where the Bible describes Mary in this way. The only place that is close is in Luke 1:28 where the angel greets Mary and indicates that she has been *given* grace, often translated as "highly favored" (κεχαριτωμένη in Greek). So, certainly Jesus was "full of grace" and Stephen was identified as being "full of grace". Yet, why does Mary also receive this ascription?