private void init() {
    inputScale = ((DecimalTypeInfo) inputTypeInfo).getScale();
    outputDecimalTypeInfo = (DecimalTypeInfo) outputTypeInfo;
  }
Value is explicitly (re)initialized in reset()
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/aggregates/VectorUDAFSumDecimal64ToDecimal.java