code: public boolean exists(BlobSourceOption... options) {
      int length = options.length;
      Storage.BlobGetOption[] getOptions = Arrays.copyOf(toGetOptions(this, options), length + 1);
      getOptions[length] = Storage.BlobGetOption.fields();
      return storage.get(getBlobId(), getOptions) != null;
    }
docs: Checks if this blob exists.
  
  <p>Example of checking if the blob exists.
  
  <pre>{@code
  boolean exists = blob.exists();
  if (exists) {
  // the blob exists
  } else {
  // the blob was not found
  }
  }</pre>
  
  @param options blob read options
  @return true if this blob exists, false otherwise
  @throws StorageException upon failure