[WFCORE-6431]: Use InputStream.nullInputStream.

[ehsavoie]

• Cleaning up the code a bit by removing the emptyStream implementation.

Jira: https://issues.redhat.com/browse/WFCORE-6431

[wildfly-ci]

Core -> Full Integration Build 12791 outcome was FAILURE using a merge of e1f54df
Summary: Tests failed: 1 (1 new), passed: 7345, ignored: 118 Build time: 03:17:14

Failed tests

org.wildfly.extension.clustering.web.DistributableWebTransformerTestCase.testRejections[0]: java.lang.RuntimeException: org.eclipse.aether.resolution.ArtifactResolutionException: Could not transfer artifact org.jboss.eap:wildfly-clustering-web-extension:jar:7.4.0.GA-redhat-00005 from/to repo0 (http://nexus.wildfly.int/nexus/repository/public/): Connect to nexus.wildfly.int:80 timed out
	at org.jboss.as.model.test.MavenUtil.createMavenGavURL(MavenUtil.java:142)
	at org.jboss.as.model.test.ChildFirstClassLoaderBuilder.addMavenResourceURL(ChildFirstClassLoaderBuilder.java:198)
	at org.jboss.as.subsystem.test.SubsystemTestDelegate$LegacyKernelServiceInitializerImpl.addMavenResourceURL(SubsystemTestDelegate.java:705)
	at org.wildfly.extension.clustering.web.DistributableWebTransformerTestCase.testRejections(DistributableWebTransformerTestCase.java:158)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
Caused by: org.eclipse.aether.resolution.ArtifactResolutionException: Could not transfer artifact org.jboss.eap:wildfly-clustering-web-extension:jar:7.4.0.GA-redhat-00005 from/to repo0 (http://nexus.wildfly.int/nexus/repository/public/): Connect to nexus.wildfly.int:80 timed out
	at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:422)
	at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:224)
	at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:201)
	at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveArtifact(DefaultRepositorySystem.java:260)
	at org.jboss.as.model.test.MavenUtil.createMavenGavURL(MavenUtil.java:140)
	... 41 more
Caused by: org.eclipse.aether.transfer.ArtifactTransferException: Could not transfer artifact org.jboss.eap:wildfly-clustering-web-extension:jar:7.4.0.GA-redhat-00005 from/to repo0 (http://nexus.wildfly.int/nexus/repository/public/): Connect to nexus.wildfly.int:80 timed out
	at org.eclipse.aether.connector.basic.ArtifactTransportListener.transferFailed(ArtifactTransportListener.java:52)
	at org.eclipse.aether.connector.basic.BasicRepositoryConnector$TaskRunner.run(BasicRepositoryConnector.java:365)
	at org.eclipse.aether.util.concurrency.RunnableErrorForwarder$1.run(RunnableErrorForwarder.java:75)
	at org.eclipse.aether.connector.basic.BasicRepositoryConnector$DirectExecutor.execute(BasicRepositoryConnector.java:583)
	at org.eclipse.aether.connector.basic.BasicRepositoryConnector.get(BasicRepositoryConnector.java:259)
	at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:498)
	at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:399)
	... 45 more
Caused by: org.apache.http.conn.ConnectTimeoutException: Connect to nexus.wildfly.int:80 timed out
	at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:123)
	at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)
	at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:326)
	at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:605)
	at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:440)
	at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:835)
	at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:72)
	at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56)
	at org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:164)
	at org.eclipse.aether.transport.http.HttpTransporter.execute(HttpTransporter.java:296)
	at org.eclipse.aether.transport.http.HttpTransporter.implGet(HttpTransporter.java:252)
	at org.eclipse.aether.spi.connector.transport.AbstractTransporter.get(AbstractTransporter.java:67)
	at org.eclipse.aether.connector.basic.BasicRepositoryConnector$GetTaskRunner.runTask(BasicRepositoryConnector.java:453)
	at org.eclipse.aether.connector.basic.BasicRepositoryConnector$TaskRunner.run(BasicRepositoryConnector.java:360)
	... 50 more

[yersan]

Let's wait for CI, but changes are harmless, so giving an approval

[yersan]

Thanks @ehsavoie