code: public static void doCastToPrimitive(MethodVisitor mv, ClassNode sourceType, ClassNode targetType) {
          mv.visitMethodInsn(INVOKEVIRTUAL, BytecodeHelper.getClassInternalName(sourceType), targetType.getName() + "Value", "()" + BytecodeHelper.getTypeDescription(targetType), false);
      }
docs: Given a wrapped number type (Byte, Integer, Short, ...), generates bytecode
  to convert it to a primitive number (int, long, double) using calls to
  wrapped.[targetType]Value()
  @param mv method visitor
  @param sourceType the wrapped number type
  @param targetType the primitive target type