GH-3158 Fix case sensitivity in binding names

Resolves #3158

Author: olegz

core/spring-cloud-stream-integration-tests/src/test/java/org/springframework/cloud/stream/binding/ExplicitBindingTests.java

@@ -27,6 +27,7 @@
 import org.springframework.boot.builder.SpringApplicationBuilder;
 import org.springframework.cloud.stream.binder.test.OutputDestination;
 import org.springframework.cloud.stream.binder.test.TestChannelBinderConfiguration;
+import org.springframework.cloud.stream.config.BindingServiceProperties;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -49,6 +50,9 @@ void explicitBindings() {
 			assertThat(context.getBean("barin", MessageChannel.class)).isNotNull();
 			assertThat(context.getBean("fooout", MessageChannel.class)).isNotNull();
 			assertThat(context.getBean("barout", MessageChannel.class)).isNotNull();
+
+			BindingServiceProperties bindingServiceProperties = context.getBean(BindingServiceProperties.class);
+			assertThat(bindingServiceProperties.getBindings().get("barOut")).isNotNull();
 		}
 	}
 

core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/config/BindingServiceProperties.java

@@ -20,6 +20,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.TreeMap;
 import java.util.concurrent.ConcurrentHashMap;
 
 import com.fasterxml.jackson.annotation.JsonInclude;
@@ -44,6 +45,7 @@
 import org.springframework.core.convert.support.GenericConversionService;
 import org.springframework.integration.support.utils.IntegrationUtils;
 import org.springframework.util.Assert;
+import org.springframework.util.LinkedCaseInsensitiveMap;
 
 /**
  * @author Dave Syer
@@ -106,7 +108,7 @@ public class BindingServiceProperties
 	 * For example; This sets the content-type for the 'input' binding of a Sink
 	 * application: 'spring.cloud.stream.bindings.input.contentType=text/plain'
 	 */
-	private Map<String, BindingProperties> bindings = new ConcurrentHashMap<>();
+	private Map<String, BindingProperties> bindings = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
 
 	/**
 	 * Additional per-binder properties (see {@link BinderProperties}) if more then one