when you say "Java is not the dominant solution in core but its quite apt among surrounding systems."

is it because of some missing capabilities or is it simply because currently banks are running on legacy applications and do not intend to switch to Java solutions while their core is already working and responsive? theoretically it seems to be possible for a new solution to use Java in any aspect or even when integrating legacy applications (mainframes, etc) into new architecture, unless there are issues in real case studies

it would be good if you could expand this point a bit more. note that this is not a prejudice over Java or anything, its only a question