Allow resolving nested placeholders if value is not String but CharSe…

…quence

See spring-projects/spring-boot#34195

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.
@@ -24,6 +24,7 @@
  *
  * @author Chris Beams
  * @author Juergen Hoeller
+ * @author Yanming Zhou
  * @since 3.1
  * @see PropertySource
  * @see PropertySources
@@ -84,8 +85,8 @@ protected <T> T getProperty(String key, Class<T> targetValueType, boolean resolv
 				}
 				Object value = propertySource.getProperty(key);
 				if (value != null) {
-					if (resolveNestedPlaceholders && value instanceof String string) {
-						value = resolveNestedPlaceholders(string);
+					if (resolveNestedPlaceholders && 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

@@ -34,6 +34,7 @@
 
 /**
  * @author Chris Beams
+ * @author Yanming Zhou
  * @since 3.1
  */
 class PropertySourcesPropertyResolverTests {
@@ -300,6 +301,43 @@ void resolveNestedPropertyPlaceholders() {
 			.withMessageContaining("Circular");
 	}
 
+	@Test
+	void resolveNestedPlaceholdersIfValueIsCharSequence() {
+		MutablePropertySources ps = new MutablePropertySources();
+		ps.addFirst(new MockPropertySource()
+				.withProperty("p1", "v1")
+				.withProperty("p2", "v2")
+				.withProperty("p3", new CharSequence() {
+
+					static final String underlying = "${p1}:${p2}";
+
+					@Override
+					public int length() {
+						return underlying.length();
+					}
+
+					@Override
+					public char charAt(int index) {
+						return underlying.charAt(index);
+					}
+
+					@Override
+					public CharSequence subSequence(int start, int end) {
+						return underlying.subSequence(start, end);
+					}
+
+					@Override
+					public String toString() {
+						return underlying;
+					}
+				})
+		);
+		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 ignoreUnresolvableNestedPlaceholdersIsConfigurable() {
 		MutablePropertySources ps = new MutablePropertySources();