@Field
    public void setPrettyPrint(boolean prettyPrint) {
        this.prettyPrint = prettyPrint;
    }
What to do if the target file already exists.  NOTE: if more than one
thread is trying write to the same file and {@link ON_EXISTS#REPLACE} is chosen,
you still might get a {@link FileAlreadyExistsException}.

@param onExists
tika-pipes/tika-emitters/tika-emitter-fs/src/main/java/org/apache/tika/pipes/emitter/fs/FileSystemEmitter.java