hollow/src/main/java/com/netflix/hollow/core/index/HollowPrefixIndex.java
protected String[] getKeys(int ordinal) {
        Object[] values = fieldPath.findValues(ordinal);
        String[] stringValues = new String[values.length];
        for (int i = 0; i < values.length; i++) {
            stringValues[i] = ((String) values[i]).toLowerCase();
        }
        return stringValues;
    }
protected String[] getKeys(int ordinal) {
        Object[] values = fieldPath.findValues(ordinal);
        String[] stringValues = new String[values.length];
        for (int i = 0; i < values.length; i++) {
            stringValues[i] = ((String) values[i]).toLowerCase();
        }
        return stringValues;
    }
Return the key to index in prefix index. Override this method to support tokens for the key. By default keys are indexed as lower case characters.
<pre>{@code
String[] keys = super.getKey(ordinal);
String[] tokens = keys[0].split(" ")
return tokens;
}</pre>

@param ordinal ordinal of the parent type.
@return keys to index.