code: public String get(String key, Charset charset)
      {
          BinaryValue wrappedKey = BinaryValue.unsafeCreate(key.getBytes(charset));
          BinaryValue value = meta.get(wrappedKey);
          if (value != null)
          {
              return value.toString(charset);
          }
          else
          {
              return null;
          }
      }
docs: Get a user metadata entry.
  <p>
  This method and its {@link RiakUserMetadata#put(java.lang.String, java.lang.String, java.nio.charset.Charset)  }
  counterpart use the supplied {@code Charset} to convert the {@code String}s.
  </p>
  
  @param key the key for the user metadata entry as a {@code String} encoded using the supplied {@code Charset}
  @return the value for the entry converted to a {@code String} using the supplied {@code Charset}