Compile difference between 6.2 and 6.3

I notice the readme is different on building from source on 6.2.x and 6.3.x. To be more specific, on 6.2.x’s readme, it says it needs boost and jdk 1.8 and on 6.3.x, there is no such mention and uses ninja. I am just wondering can I use 6.3 instruction to compile for 6.2 (ie, without installing jdk). Would that work?

Probably not. 6.2 and before we use Makefile based build. In 6.3, we switch to cmake/ninja based build system, which is not available or tested for 6.2.