code: private Stream<ConstraintRelationshipInfo> constraintsForRelationship(Map<String,Object> config) {
          Schema schema = db.schema();
  
          SchemaConfig schemaConfig = new SchemaConfig(config);
          Set<String> includeRelationships = schemaConfig.getRelationships();
          Set<String> excludeRelationships = schemaConfig.getExcludeRelationships();
  
          try ( Statement ignore = tx.acquireStatement() ) {
              TokenRead tokenRead = tx.tokenRead();
              Iterable<ConstraintDefinition> constraintsIterator;
  
              if(!includeRelationships.isEmpty()) {
                  constraintsIterator = includeRelationships.stream()
                          .filter(type -> !excludeRelationships.contains(type) && tokenRead.relationshipType(type) != -1)
                          .flatMap(type -> {
                              Iterable<ConstraintDefinition> constraintsForType = schema.getConstraints(RelationshipType.withName(type));
                              return StreamSupport.stream(constraintsForType.spliterator(), false);
                          })
                          .collect(Collectors.toList());
              } else {
                  Iterable<ConstraintDefinition> allConstraints = schema.getConstraints();
                  constraintsIterator = StreamSupport.stream(allConstraints.spliterator(),false)
                          .filter(index -> !excludeRelationships.contains(index.getRelationshipType().name()))
                          .collect(Collectors.toList());
              }
  
              Stream<ConstraintRelationshipInfo> constraintRelationshipInfoStream = StreamSupport.stream(constraintsIterator.spliterator(), false)
                      .filter(constraintDefinition -> constraintDefinition.isConstraintType(ConstraintType.RELATIONSHIP_PROPERTY_EXISTENCE))
                      .map(this::relationshipInfoFromConstraintDefinition);
  
              return constraintRelationshipInfoStream;
          }
      }
docs: Collects constraints for relationships
  
  @return