Comparator class finding zero matches while using with classParams parameter

Problem

A match rule has started to return zero matches once a parameter has been passed to one of its base Comparators through the classParams parameter.

Example:

"parameters": [
    {
        "parameter": "groups",
        "values": [
        {
        "classParams": {
            "pattern": "[a-z]"
        },
        "className": "com.reltio.match.comparator.MetaphoneComparator"
    }
]

Solution

The reason for returning no matches is that the MetaphoneComparator does not work with the class parameter "pattern". No matter what value is passed here, the rule will return no matches because the parameter is unrecognized. In this case, the "pattern" parameter can be passed to the CustomComparator like below: 

"parameters": [
    {
        "parameter": "groups",
        "values": [
        {
        "pattern": "[a-z]";
        }  
    }
],
"className": "com.reltio.match.comparator.CustomComparator"