Custom Date format with brackets

[paiz1556]

Here is my sample log file:

20:54:50,406 TRACE [com.test.my.process.module.GARBAGE06] (Thread-15 (ActiveMQ-client-global-threads-1006309389)) [2019-06-07][20:04:12][5239354][TESTTRN  ][GARBAGE06                 ][coreProcess - EXIT            ]

The date I need to parse is the 2 parts in brackets
[2019-06-07][20:04:12]

What is the best way to get that out in a usable date format? It doesn't appear that there is a PATTERN set up that matches this.

[Badger]

    grok {
        match => { "message" => '\[(?<[@metadata][date]>%{YEAR}-%{MONTHNUM}-%{MONTHDAY})\]\[%{TIME:[@metadata][time]}' }
        add_field => { "[@metadata][ts]" => "%{[@metadata][date]} %{[@metadata][time]}" }
    }
    date { match => [ "[@metadata][ts]", "YYYY-MM-dd HH:mm:ss" ] }