How to define & use EO Custom Properties ADF

• Define the custom property under Entity Object's Attribute
• Define Entity Definition Class 
  
• Override resolveDefObject() method and set Property Expression for the attribute where the CP was defined
• Refer the custom property as #{bindings.namOfTheAttibute.hints.nameOfTheCustomProperty}

http://adfpractice-fedor.blogspot.com/2014/03/groovy-expressions-in-custom-attribute.html