ContentHashable (Alluxio Core - Common Utilities 300 API)

All Known Implementing Classes:

AtomicFileOutputStream, ObjectLowLevelOutputStream
```
public interface ContentHashable
```
Interface for returning the content hash. Instances of OutputStream returned by UnderFileSystem.create(java.lang.String) may implement this interface if the UFS returns the hash of the content written when the stream is closed. The content hash will then be used as part of the metadata fingerprint when the file is completed on the Alluxio master.

- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method Description
  
  java.util.Optional<java.lang.String> getContentHash()

- Method Detail
  - getContentHash
```
java.util.Optional<java.lang.String> getContentHash()
                                             throws java.io.IOException
```
    Returns:
    
    the content hash of the file written to the UFS if available after the stream has been closed
    
    Throws:
    
    java.io.IOException