@Override
    public boolean equals(Object o) {
        if (o == null) return false;
        if (!(o.getClass().equals(this.getClass()))) return false;
        PlacementSpec other = (PlacementSpec) o;
        return startPartition == other.startPartition &&
            numPartitions == other.numPartitions &&
            numReplicas == other.numReplicas;
    }
Specifies a replica placement that we want to make.
metadata/src/main/java/org/apache/kafka/metadata/placement/PlacementSpec.java