code: public void setTargetBytecode(String version) {
          for (String allowedJdk : ALLOWED_JDKS) {
              if (allowedJdk.equals(version)) {
                  this.targetBytecode = version;
              }
          }
      }
docs: Allow setting the bytecode compatibility. The parameter can take
  one of the values <tt>1.7</tt>, <tt>1.6</tt>, <tt>1.5</tt> or <tt>1.4</tt>.
  If wrong parameter then the value will default to VM determined version.
  
  @param version the bytecode compatibility mode