As described by Jenny in JDK-8065344 some of the log messages are missing a ":".

Here's are the comments regarding ":" from JDK-8065344:

Parallel Redirty>Parallel Redirty:
 -Other phases has ':' as separator, except for this one.

[34.589s][debug ][gc,ergo,cset] GC(6) Added expensive regions to CSet (old CSet region num not reached min).old 2940 regions, expensive: 2940 regions, min 2940 regions, remaining time: 0.00ms
->[34.589s][debug ][gc,ergo,cset] GC(6) Added expensive regions to CSet (old CSet region num not reached min).old: 2940 regions, expensive: 2940 regions, min: 2940 regions, remaining time: 0.00ms
By adding ":" after old, expensive, min to make the format the same.

Finish choosing CSet. old 0 regions, predicted old region time: 0.00ms, time remaining: 0.00
-> Finish choosing CSet. old: 0 regions, predicted old region time: 0.00ms, time remaining: 0.00
The ':' after old makes the format the same