code: package it.unibz.inf.ontop.generation.algebra;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.model.term.ImmutableExpression;
  
  import java.util.Optional;
  
  /**
   * Abstraction for LeftJoinRelation and explicit InnerJoinRelation
   */
  public interface BinaryJoinExpression extends SQLExpression {
  
      SQLExpression getLeft();
      SQLExpression getRight();
  
      Optional<ImmutableExpression> getFilterCondition();
  
      ImmutableList<? extends SQLExpression> getSubExpressions();
  
  
  }
  