private JetType getPrimitiveType(char descriptor, boolean nullable) {
   if (!nullable) {
     for (JvmPrimitiveType jvmPrimitiveType : JvmPrimitiveType.values()) {
       if (jvmPrimitiveType.getJvmLetter() == descriptor) {
         return jetStandardLibrary.getPrimitiveJetType(jvmPrimitiveType.getPrimitiveType());
       }
     }
     if (descriptor == 'V') {
       return JetStandardClasses.getUnitType();
     }
   } else {
     for (JvmPrimitiveType jvmPrimitiveType : JvmPrimitiveType.values()) {
       if (jvmPrimitiveType.getJvmLetter() == descriptor) {
         return jetStandardLibrary.getNullablePrimitiveJetType(
             jvmPrimitiveType.getPrimitiveType());
       }
     }
     if (descriptor == 'V') {
       throw new IllegalStateException("incorrect signature: nullable void");
     }
   }
   throw new IllegalStateException("incorrect signature");
 }