add the ` if not exists ' condition to this create index statement . concode_field_sep boolean ifNotExists concode_elem_sep String indexName concode_elem_sep boolean keys concode_elem_sep Optional<String> keyspaceName concode_elem_sep String tableName concode_elem_sep String columnName concode_field_sep CreateIndexOn onTable concode_elem_sep CreateIndexOn onTable concode_elem_sep SchemaStatement andKeysOfColumn concode_elem_sep String buildInternal concode_elem_sep SchemaStatement andColumn
CreateIndex function ( ) { this . ifNotExists = true ; return this ; }