PropertySourcesLoader with highest precedence should win

Fixes gh-13955

Author: mbhave

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigFileApplicationListener.java

@@ -459,15 +459,20 @@ private void load(String location, String name, Profile profile,
 					if (canLoadFileExtension(loader, location)) {
 						load(loader, location, profile,
 								filterFactory.getDocumentFilter(profile), consumer);
+						return;
 					}
 				}
 			}
+			Set<String> processedExtensions = new HashSet<>();
 			for (PropertySourceLoader loader : this.propertySourceLoaders) {
 				for (String fileExtension : loader.getFileExtensions()) {
-					String prefix = location + name;
-					fileExtension = "." + fileExtension;
-					loadForFileExtension(loader, prefix, fileExtension, profile,
-							filterFactory, consumer);
+					if (!processedExtensions.contains(fileExtension)) {
+						processedExtensions.add(fileExtension);
+						String prefix = location + name;
+						fileExtension = "." + fileExtension;
+						loadForFileExtension(loader, prefix, fileExtension, profile,
+								filterFactory, consumer);
+					}
 				}
 			}
 		}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigFileApplicationListenerTests.java

@@ -926,6 +926,21 @@ public void multiValueSpringProfiles() {
 		assertThat(environment.getProperty("message")).isEqualTo("multiprofile");
 	}
 
+	@Test
+	public void propertiesFromCustomPropertySourceLoaderShouldBeUsed() {
+		this.initializer.postProcessEnvironment(this.environment, this.application);
+		assertThat(this.environment.getProperty("customloader1")).isEqualTo("true");
+	}
+
+	@Test
+	public void propertiesFromCustomPropertySourceLoaderShouldBeUsedWithSpecificResource() {
+		String location = "classpath:application.custom";
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.environment,
+				"spring.config.location=" + location);
+		this.initializer.postProcessEnvironment(this.environment, this.application);
+		assertThat(this.environment.getProperty("customloader1")).isEqualTo("true");
+	}
+
 	private Condition<ConfigurableEnvironment> matchingPropertySource(
 			final String sourceName) {
 		return new Condition<ConfigurableEnvironment>(
@@ -1018,7 +1033,7 @@ private static class LowestPrecedenceEnvironmentPostProcessor
 		@Override
 		public void postProcessEnvironment(ConfigurableEnvironment environment,
 				SpringApplication application) {
-			assertThat(environment.getPropertySources()).hasSize(4);
+			assertThat(environment.getPropertySources()).hasSize(5);
 		}
 
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/TestPropertySourceLoader1.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.boot.context.config;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.boot.env.PropertySourceLoader;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.io.Resource;
+
+/**
+ * {@link PropertySourceLoader} for tests.
+ *
+ * @author Madhura Bhave
+ */
+class TestPropertySourceLoader1 implements PropertySourceLoader {
+
+	@Override
+	public String[] getFileExtensions() {
+		return new String[] { "custom" };
+	}
+
+	@Override
+	public List<PropertySource<?>> load(String name, Resource resource)
+			throws IOException {
+		Map<String, Object> map = Collections.singletonMap("customloader1", "true");
+		return Collections.singletonList(new MapPropertySource(name, map));
+	}
+
+}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/TestPropertySourceLoader2.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.boot.context.config;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.boot.env.PropertySourceLoader;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.io.Resource;
+
+/**
+ * {@link PropertySourceLoader} for tests.
+ *
+ * @author Madhura Bhave
+ */
+class TestPropertySourceLoader2 implements PropertySourceLoader {
+
+	@Override
+	public String[] getFileExtensions() {
+		return new String[] { "custom" };
+	}
+
+	@Override
+	public List<PropertySource<?>> load(String name, Resource resource)
+			throws IOException {
+		Map<String, Object> map = Collections.singletonMap("customloader2", "true");
+		return Collections.singletonList(new MapPropertySource(name, map));
+	}
+
+}

spring-boot-project/spring-boot/src/test/resources/META-INF/spring.factories

@@ -0,0 +1,3 @@
+org.springframework.boot.env.PropertySourceLoader=\
+org.springframework.boot.context.config.TestPropertySourceLoader1,\
+org.springframework.boot.context.config.TestPropertySourceLoader2