Function existsById

existsById(annotationId): boolean
JMap.Application.Annotation.existsById

Returns true if annotation exists for the given id, else false
Parameters
- annotationId: string
  the given annotation id
Returns boolean
Throws
if the annotationId param is not a valid string

Example
```
// return true if annotation exists, else false
JMap.Application.Annotation.existsById("d68385b01be3c241c7b6298b2788839d")
```