presto-memory/src/main/java/io/prestosql/plugin/memory/MemoryColumnHandle.java/MemoryColumnHandle/equals
class MemoryColumnHandle:    @Override
    public boolean equals(Object obj)
    {
        if (this == obj) {
            return true;
        }
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }
        MemoryColumnHandle other = (MemoryColumnHandle) obj;
        return Objects.equals(this.columnIndex, other.columnIndex);
    }