Extension (HAPI FHIR - Core Library 5.4.0-PRE1-SNAPSHOT API)

```
@Target(FIELD)
@Retention(RUNTIME)
public @interface Extension
```
Field modifier to be placed on a child field (a field also annotated with the Child annotation) which indicates that this field is an extension.

Required Element Summary

Required Elements
Modifier and Type	Required Element	Description
`boolean`	`definedLocally`	This parameter affects how the extension is treated when the element definition containing this resource is exported to a profile.
`boolean`	`isModifier`	Returns `true` if this extension is a modifier extension
`String`	`url`	The URL associated with this extension

- Element Detail
  - definedLocally
```
boolean definedLocally
```
    This parameter affects how the extension is treated when the element definition containing this resource is exported to a profile.
    If set to true, the resource is taken to be a local resource and its definition is exported along with the reference. Use this option for extension defintions that you have added locally (i.e. within your own organization)
    
    If set to false, the resource is taken to be a remote resource and its definition is not exported to the profile. Use this option for extensions that are defined by other organizations (i.e. by regional authorities or jurisdictional governments)
- - isModifier
```
boolean isModifier
```
    Returns true if this extension is a modifier extension
- - url
```
String url
```
    The URL associated with this extension