Polish "Resolved nested placeholder for CharSequence"

See gh-32876

spring-core/src/main/java/org/springframework/core/env/PropertySourcesPropertyResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -84,8 +84,10 @@ public class PropertySourcesPropertyResolver extends AbstractPropertyResolver {
 				}
 				Object value = propertySource.getProperty(key);
 				if (value != null) {
-					if (resolveNestedPlaceholders && value instanceof String string) {
-						value = resolveNestedPlaceholders(string);
+					if (resolveNestedPlaceholders &&
+							(String.class.equals(targetValueType) || CharSequence.class.equals(targetValueType)) &&
+							value instanceof CharSequence cs) {
+						value = resolveNestedPlaceholders(cs.toString());
 					}
 					logKeyFound(key, propertySource, value);
 					return convertValueIfNecessary(value, targetValueType);

spring-core/src/test/java/org/springframework/core/env/PropertySourcesPropertyResolverTests.java

@@ -300,6 +300,31 @@ class PropertySourcesPropertyResolverTests {
 			.withMessageContaining("Circular");
 	}
 
+	@Test
+	void resolveNestedPlaceholdersIfValueIsCharSequence() {
+		MutablePropertySources ps = new MutablePropertySources();
+		ps.addFirst(new MockPropertySource()
+				.withProperty("p1", "v1")
+				.withProperty("p2", "v2")
+				.withProperty("p3", new StringBuilder("${p1}:${p2}")));
+		ConfigurablePropertyResolver pr = new PropertySourcesPropertyResolver(ps);
+		assertThat(pr.getProperty("p1")).isEqualTo("v1");
+		assertThat(pr.getProperty("p2")).isEqualTo("v2");
+		assertThat(pr.getProperty("p3")).isEqualTo("v1:v2");
+	}
+
+	@Test
+	void resolveNestedPlaceholdersIfValueIsCharSequenceAndStringBuilderIsRequested() {
+		MutablePropertySources ps = new MutablePropertySources();
+		ps.addFirst(new MockPropertySource()
+				.withProperty("p1", "v1")
+				.withProperty("p2", "v2")
+				.withProperty("p3", new StringBuilder("${p1}:${p2}")));
+		ConfigurablePropertyResolver pr = new PropertySourcesPropertyResolver(ps);
+		assertThat(pr.getProperty("p3", StringBuilder.class)).isInstanceOf(StringBuilder.class)
+				.hasToString("${p1}:${p2}");
+	}
+
 	@Test
 	void ignoreUnresolvableNestedPlaceholdersIsConfigurable() {
 		MutablePropertySources ps = new MutablePropertySources();