Fix conversion failures when using DefaultResolver

Update `ConfigurationPropertySourcesPropertyResolver` so that calls to
the `DefaultResolver` do not attempt conversion.

Prior to this commit, the delegate resolver was accidentally called
with the target type which could cause a `ConversionFailedException`
to be thrown. We should have always used `Object.class` and let the
`convertValueIfNecessary` method perform conversion.

Fixes gh-26732

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

@@ -71,7 +71,7 @@ protected String getPropertyAsRawString(String key) {
 	}
 
 	private <T> T getProperty(String key, Class<T> targetValueType, boolean resolveNestedPlaceholders) {
-		Object value = findPropertyValue(key, targetValueType);
+		Object value = findPropertyValue(key);
 		if (value == null) {
 			return null;
 		}
@@ -81,7 +81,7 @@ private <T> T getProperty(String key, Class<T> targetValueType, boolean resolveN
 		return convertValueIfNecessary(value, targetValueType);
 	}
 
-	private Object findPropertyValue(String key, Class<?> targetValueType) {
+	private Object findPropertyValue(String key) {
 		ConfigurationPropertySourcesPropertySource attached = getAttached();
 		if (attached != null) {
 			ConfigurationPropertyName name = ConfigurationPropertyName.of(key, true);
@@ -94,7 +94,7 @@ private Object findPropertyValue(String key, Class<?> targetValueType) {
 				}
 			}
 		}
-		return this.defaultResolver.getProperty(key, targetValueType, false);
+		return this.defaultResolver.getProperty(key, Object.class, false);
 	}
 
 	private ConfigurationPropertySourcesPropertySource getAttached() {

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

@@ -102,6 +102,17 @@ void getPropertyWhenNotAttached() {
 		assertThat(propertySource.getCount("sprong")).isEqualTo(1);
 	}
 
+	@Test // gh-26732
+	void getPropertyAsTypeWhenHasPlaceholder() {
+		ResolverEnvironment environment = new ResolverEnvironment();
+		MockPropertySource propertySource = new MockPropertySource();
+		propertySource.withProperty("v1", "1");
+		propertySource.withProperty("v2", "${v1}");
+		environment.getPropertySources().addFirst(propertySource);
+		assertThat(environment.getProperty("v2")).isEqualTo("1");
+		assertThat(environment.getProperty("v2", Integer.class)).isEqualTo(1);
+	}
+
 	private CountingMockPropertySource createMockPropertySource(StandardEnvironment environment, boolean attach) {
 		CountingMockPropertySource propertySource = new CountingMockPropertySource();
 		propertySource.withProperty("spring", "boot");