There is no statement being made here , overtly or covertly. The Chinese always tend to get hyper whenever any of their "perceived " enemies do deals between themselves.
If India is building a strategic relationship with Japan , how does that automatically equate to "containing" China ? We , do business with China as we do business with Japan .
Our only goal is to improve our technological base. Chinese thinktanks may misconstrue this in a myriad of ways but if a commercial deal ( which by the way does not even involve any serious weaponry but only transport type aircraft as I understand ) starts ringing alarm bells in our neighborhood then there is nothing we can do about it.
We are not going to roll back our strategic co-operation with an advanced society with much to offer , just because of Chinese concerns.
Hell , the Chinese never really appreciated our concerns when collaborating with Pakistan in Nuclear Technology , active defense co-operation, Energy security ( remember the Gwadar port) etc etc. So why are they so hysterical about Japan's co-operation with India ?
Its time that Chinese come to terms with Geo-political realities and stop trying to impose their perspectives on others.
Why ---when India launched an Israeli spy Sat , the Iranians protested --we explained to them it was a commercial launch and done as a quid-pro-quo for Israeli technology transfer to our own satellite Risat.
That is the best explanation Indian Diplomacy has for the Chinese who are concerned. Learn to live with it.