code: @Override
     public ValidationErrors validate(final CreateSpatialIndexStatement statement,
           final Database database, final SqlGeneratorChain sqlGeneratorChain) {
        final ValidationErrors validationErrors = new ValidationErrors();
        validationErrors.checkRequiredField("tableName", statement.getTableName());
        validationErrors.checkRequiredField("columns", statement.getColumns());
        return validationErrors;
     }
docs: Ensures that the table name and columns are populated.
  
  @see SqlGenerator#validate(liquibase.statement.SqlStatement, Database, SqlGeneratorChain)