common/src/main/java/com/streamsets/pipeline/lib/parser/shaded/com/google/code/regexp/Pattern.java
public List<String> groupNames() {
        if (groupNames == null) {
            groupNames = new ArrayList<String>(groupInfo.keySet());
        }
        return groupNames;
    }
public List<String> groupNames() {
        if (groupNames == null) {
            groupNames = new ArrayList<String>(groupInfo.keySet());
        }
        return groupNames;
    }
Gets the names of all capture groups

@return the list of names