Project: mule
Issue MULE-8069: Define a richer set of expression aware XSD types 
Now that the extensions api is going to make the parsing of expressions easier and enabled by default on every component, we should define new XSD types which bette reflect the expected return types. For example: * expressionSubstitutableString * expressionSubstitutableInt * etc Things to discuss and define: * Do we always allow embedded expressions? * is "#[foo] " a valid expression?
Story points: 8