public static float getFloatVar(Configuration conf, ConfVars var, float defaultVal) {
    if (var.altName != null) {
      return conf.getFloat(var.varname, conf.getFloat(var.altName, defaultVal));
    }
    return conf.getFloat(var.varname, defaultVal);
  }
Writes the default ConfVars out to a byte array and returns an input
stream wrapping that byte array.

We need this in order to initialize the ConfVar properties
in the underling Configuration object using the addResource(InputStream)
method.

It is important to use a LoopingByteArrayInputStream because it turns out
addResource(InputStream) is broken since Configuration tries to read the
entire contents of the same InputStream repeatedly without resetting it.
LoopingByteArrayInputStream has special logic to handle this.
common/src/java/org/apache/hadoop/hive/conf/HiveConf.java