code: public static Type hsqlTypeFromVoltType(VoltType voltReturnType) {
          Class<?> typeClass = VoltType.classFromByteValue(voltReturnType.getValue());
          int typeNo = Types.getParameterSQLTypeNumber(typeClass);
          return Type.getDefaultTypeWithSize(typeNo);
      }
docs: Convert a VoltType to an HSQL type.
  
  Types are somewhat confusing.  There are three type representations, all different.
  <ol>
  <li> Some types are in HSQL.  These are enumerals of the type org.hsqldb_voltpatches.types.Type.</li>
  <li> Some types are in VoltDB.  These are enumerals of the type org.voltdb.VoltType.</li>
  <li> Some types are Java class types.  These have the type Class<?>, and come from the JVM.</li>
  <ol>
  Neeedless to say, these three all have entirely different structures.  The HSQL types are used here
  in HSQl.  The VoltType enumerals  are used in the rest of Volt.  In particular, the functions we need
  to convert from VoltType to Type, like getParameterSQLTypeNumber, are not visible outside of HSQL.  So
  we we need this function to convert one way.  Conversions the other way are possible, but not
  currently needed.
  
  @param voltReturnType
  @return