public AggregateParser<C, O> build() {
        return new AggregateParserBuilder<>(Arrays.asList(this.first, this.second)).withMapper(
                this.outType,
                (commandContext, aggregateContext) -> {
                    final U firstResult = aggregateContext.get(this.first.name());
                    final V secondResult = aggregateContext.get(this.second.name());
                    return this.mapper.map(commandContext, firstResult, secondResult);
                }
        ).build();
    }
Builds an {@link AggregateParser} from the current state of the builder.

@return the built {@link AggregateParser}
cloud-core/src/main/java/org/incendo/cloud/parser/aggregate/AggregateParserPairBuilder.java