Identifier (LinkML-Java 0.1.0 API)

```
@Retention(RUNTIME)
@Target(FIELD)
public @interface Identifier
```
An annotation to indicate that a field is intended to contain a unique identifier for an instance of the class it belongs to.
Of note, in LinkML an identifier field is necessarily a RequirementLevel.MANDATORY field.
The same annotation can also indicate that a field is intended to contain a local unique identifier – what LinkML calls a key. A key is similar to a (global) identifier, but (1) it only needs to be unique within the collection where it appears (instead of within the entire LinkML context), and (2) consequently it cannot be referenced globally (an object identified by a key can only be inlined).
Use isGlobal=false to mark the field as a key. The default is isGlobal=true, which marks the field as a (global) identifier.

- Optional Element Summary
  
  Optional Elements
  Modifier and Type Optional Element Description
  
  boolean isGlobal

- Element Detail
  - isGlobal
```
boolean isGlobal
```
    Default:
    
    true