@Override
  public void fromData(DataInput in,
      DeserializationContext context) throws IOException, ClassNotFoundException {
    name = in.readUTF();
    expression = in.readUTF();
    fromClause = in.readUTF();
    loadEntries = in.readBoolean();

    byte byteIndexType = in.readByte();
    if (0 == byteIndexType) {
      indexType = IndexType.PRIMARY_KEY;
    } else if (1 == byteIndexType) {
      indexType = IndexType.HASH;
    } else {
      indexType = IndexType.FUNCTIONAL;
    }

    boolean isImportStr = in.readBoolean();
    if (isImportStr) {
      importStr = in.readUTF();
    }
  }
This class contains the information needed to create an index It will contain the callback data
between <index></index> invocation
geode-core/src/main/java/org/apache/geode/cache/query/internal/index/IndexCreationData.java