@Override public Builder ensureSchema(boolean ensureSchema) {
      return super.ensureSchema(ensureSchema);
    }
Ensures that schema exists, if enabled tries to execute:
<ol>
  <li>io.zipkin.zipkin2:zipkin-storage-cassandra/zipkin2-schema.cql</li>
  <li>io.zipkin.zipkin2:zipkin-storage-cassandra/zipkin2-indexes.cql</li>
</ol>
Defaults to true.
zipkin-storage/cassandra/src/main/java/zipkin2/storage/cassandra/CassandraStorage.java