Fix caching issues with map property sources

Update `SpringIterableConfigurationPropertySource` so that the cache
key from a `MapPropertySource` is invalidated when the map contents
changes.

Prior to this commit, the actual keys of the map were used as the key.
This meant that if the underlying map changed, they key wouldn't be
invalidated because it ultimately pointed to the same object instance.

See gh-13344

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SpringIterableConfigurationPropertySource.java

@@ -142,9 +142,7 @@ class SpringIterableConfigurationPropertySource extends SpringConfigurationPrope
 	}
 
 	private Object getCacheKey() {
-		if (getPropertySource() instanceof MapPropertySource) {
-			return ((MapPropertySource) getPropertySource()).getSource().keySet();
-		}
+		// gh-13344
 		return getPropertySource().getPropertyNames();
 	}
 

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java

@@ -76,6 +76,7 @@ import static org.hamcrest.Matchers.not;
  * @author Andy Wilkinson
  * @author Stephane Nicoll
  * @author Ben Hale
+ * @author Fahim Farook
  */
 @RunWith(ModifiedClassPathRunner.class)
 @ClassPathExclusions("log4j*.jar")
@@ -500,12 +501,23 @@ public class LoggingApplicationListenerTests {
 	@Test
 	public void environmentPropertiesIgnoreUnresolvablePlaceholders() {
 		// gh-7719
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context,
+				"logging.pattern.console=console ${doesnotexist}");
+		this.initializer.initialize(this.context.getEnvironment(),
+				this.context.getClassLoader());
+		assertThat(System.getProperty(LoggingSystemProperties.CONSOLE_LOG_PATTERN))
+				.isEqualTo("console ${doesnotexist}");
+	}
+
+	@Test
+	public void environmentPropertiesResolvePlaceholders() {
 		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context,
 				"logging.pattern.console=console ${pid}");
 		this.initializer.initialize(this.context.getEnvironment(),
 				this.context.getClassLoader());
 		assertThat(System.getProperty(LoggingSystemProperties.CONSOLE_LOG_PATTERN))
-				.isEqualTo("console ${pid}");
+				.isEqualTo(this.context.getEnvironment()
+						.getProperty("logging.pattern.console"));
 	}
 
 	@Test

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/source/SpringIterableConfigurationPropertySourceTests.java

@@ -37,6 +37,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author Phillip Webb
  * @author Madhura Bhave
+ * @author Fahim Farook
  */
 public class SpringIterableConfigurationPropertySourceTests {
 
@@ -157,6 +158,24 @@ public class SpringIterableConfigurationPropertySourceTests {
 				.isEqualTo(ConfigurationPropertyState.ABSENT);
 	}
 
+	@SuppressWarnings("unchecked")
+	@Test
+	public void propertySourceChangeReflects() {
+		// gh-13344
+		final Map<String, Object> source = new LinkedHashMap<>();
+		source.put("key1", "value1");
+		source.put("key2", "value2");
+		final EnumerablePropertySource<?> propertySource = new MapPropertySource("test",
+				source);
+		final SpringIterableConfigurationPropertySource adapter = new SpringIterableConfigurationPropertySource(
+				propertySource, DefaultPropertyMapper.INSTANCE);
+		assertThat(adapter.stream().count()).isEqualTo(2);
+
+		((Map<String, Object>) adapter.getPropertySource().getSource()).put("key3",
+				"value3");
+		assertThat(adapter.stream().count()).isEqualTo(3);
+	}
+
 	/**
 	 * Test {@link PropertySource} that's also an {@link OriginLookup}.
 	 */