Deprecated (Alluxio Core - Common Utilities 294 API)

```
@Retention(RUNTIME)
public @interface Deprecated
```
An annotation for PropertyKeys that can be used to mark a key as deprecated (slated for removal). If a key is marked with this annotation, then any Alluxio processes should trigger log warning messages upon configuration validation. This annotation is provided as an alternative to Deprecated. Both annotations do not need to be specified on a key. The advantage of using this annotation is that we can supply a custom message rather than simply telling the user "This key has been deprecated".

- Optional Element Summary
  
  Optional Elements
  Modifier and Type Optional Element Description
  
  java.lang.String message
  A message to the user which could suggest an alternative key.

- Element Detail
  - message
```
java.lang.String message
```
    A message to the user which could suggest an alternative key. The message should not mention anything about deprecation, but rather alternatives, side-effects, and/or the time-frame for removal of the key. An example may be: "This key is slated for removal in v2.0. An equivalent configuration property is alluxio.x.y.z." or "This key is slated for removal in v3.0. Afterwards, this value will no longer be configurable"
    
    Returns:
    
    A string explaining deprecation
    
    Default:
    
    ""