private String getVectorPrimitiveType(String columnVectorType) throws Exception {
    if (columnVectorType.equals("LongColumnVector")) {
      return "long";
    } else if (columnVectorType.equals("double")) {
      return "double";
    } else if (columnVectorType.equals("DecimalColumnVector")) {
      return "decimal";
    } else if (columnVectorType.equals("BytesColumnVector")) {
      return "string";
    }
    throw new Exception("Could not determine primitive type for column vector type: " + columnVectorType);
  }
Return the argument with the first letter capitalized
vector-code-gen/src/org/apache/hadoop/hive/tools/GenVectorCode.java