4.x: MpConfigSources.create does not handle empty values

[romain-grecourt]

Environment Details

• Helidon Version: 4.1.4
• Helidon MP

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Problem Description

io.helidon.config.mp.MpConfigSources.create does not handle empty values (I.e. ""), which then results in java.util.NoSuchElementException because the MicroProfile config specification does not support empty values.

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The following code detaches SE config as a map

helidon/microprofile/messaging/core/src/main/java/io/helidon/microprofile/messaging/AdHocConfigBuilder.java

Line 48 in f57be59

configuration.putAll(configToPut.detach().asMap().orElse(Map.of()));

And then builds a MicroProfile Config from the map:

helidon/microprofile/messaging/core/src/main/java/io/helidon/microprofile/messaging/AdHocConfigBuilder.java

Line 55 in f57be59

.withSources(MpConfigSources.create(configuration))

This makes it impossible to supply the following configuration:

mp.messaging:
  connector:
      helidon-kafka:
        ssl.endpoint.identification.algorithm: ${EMPTY}

Exception in thread "main" java.util.NoSuchElementException: Property "ssl.endpoint.identification.algorithm" is not available in configuration
	at io.helidon.config.mp.MpConfigImpl.lambda$getValue$2(MpConfigImpl.java:127)
	at java.base/java.util.Optional.orElseThrow(Optional.java:403)
	at io.helidon.config.mp.MpConfigImpl.getValue(MpConfigImpl.java:127)
	at io.helidon.config.mp.SeConfig.asMap(SeConfig.java:262)
	at io.helidon.messaging.connectors.kafka.KafkaConfig.create(KafkaConfig.java:63)
	at io.helidon.messaging.connectors.kafka.KafkaPublisher$Builder.config(KafkaPublisher.java:373)
	at io.helidon.messaging.connectors.kafka.KafkaConnector.getPublisherBuilder(KafkaConnector.java:197)
	at io.helidon.messaging.connectors.kafka.KafkaConnector$Proxy$_$$_WeldClientProxy.getPublisherBuilder(Unknown Source)
	at io.helidon.microprofile.messaging.OutgoingConnector.lambda$getPublisher$0(OutgoingConnector.java:74)
	at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1228)
	at io.helidon.microprofile.messaging.OutgoingConnector.getPublisher(OutgoingConnector.java:73)
	at io.helidon.microprofile.messaging.UniversalChannel.connect(UniversalChannel.java:130)
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
	at java.base/java.util.HashMap$ValueSpliterator.forEachRemaining(HashMap.java:1787)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596)
	at io.helidon.microprofile.messaging.ChannelRouter.connect(ChannelRouter.java:90)
	at io.helidon.microprofile.messaging.MessagingCdiExtension.makeConnections(MessagingCdiExtension.java:187)

Steps to reproduce

@Test
void testEmptyValue() {
    org.eclipse.microprofile.config.Config config = ConfigProviderResolver.instance()
            .getBuilder()
            .withSources(MpConfigSources.create(Map.of("key", "")))
            .build();
    assertThat(config.getValue("key", String.class), is(""));
}

[Captain1653]

Should this issue be backported for 3.x? I can do it if necessary.

[romain-grecourt]

Yes, feel free to create a PR.