ref~ is shorthand for ref~1 and means the commit's first parent. ref~2 means the commit's first parent's first parent. ref~3 means the commit's first parent's first parent's first parent. And so on.
ref^ is shorthand for ref^1 and means the commit's first parent. But where the two differ is that ref^2 means the commit's second parent (remember, commits can have two parents when they are a merge).
You can upgrade your Java 7 version to 1.7.0_131-b31
For JRE 1.7.0_131-b31 in Oracle site :
TLSv1.2 and TLSv1.1 are now enabled by default on the TLS client end-points. This is similar behavior to what already happens in JDK 8 releases.