Merge branch '6.2.x'

# Conflicts:
#	spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultListableBeanFactory.java
#	spring-jdbc/src/main/java/org/springframework/jdbc/core/StatementCreatorUtils.java

spring-core/src/main/java/org/springframework/cglib/core/ReflectUtils.java

@@ -527,15 +527,26 @@ public class ReflectUtils {
 				c = lookup.defineClass(b);
 			}
 			catch (LinkageError | IllegalAccessException ex) {
-				throw new CodeGenerationException(ex) {
-					@Override
-					public String getMessage() {
-						return "ClassLoader mismatch for [" + contextClass.getName() +
-								"]: JVM should be started with --add-opens=java.base/java.lang=ALL-UNNAMED " +
-								"for ClassLoader.defineClass to be accessible on " + loader.getClass().getName() +
-								"; consider co-locating the affected class in that target ClassLoader instead.";
+				if (ex instanceof LinkageError) {
+					// Could be a ClassLoader mismatch with the class pre-existing in a
+					// parent ClassLoader -> try loadClass before giving up completely.
+					try {
+						c = contextClass.getClassLoader().loadClass(className);
 					}
-				};
+					catch (ClassNotFoundException cnfe) {
+					}
+				}
+				if (c == null) {
+					throw new CodeGenerationException(ex) {
+						@Override
+						public String getMessage() {
+							return "ClassLoader mismatch for [" + contextClass.getName() +
+									"]: JVM should be started with --add-opens=java.base/java.lang=ALL-UNNAMED " +
+									"for ClassLoader.defineClass to be accessible on " + loader.getClass().getName() +
+									"; consider co-locating the affected class in that target ClassLoader instead.";
+						}
+					};
+				}
 			}
 			catch (Throwable ex) {
 				throw new CodeGenerationException(ex);

spring-core/src/main/java/org/springframework/core/SpringProperties.java

@@ -117,7 +117,18 @@ public final class SpringProperties {
 	 * @param key the property key
 	 */
 	public static void setFlag(String key) {
-		localProperties.put(key, Boolean.TRUE.toString());
+		localProperties.setProperty(key, Boolean.TRUE.toString());
+	}
+
+	/**
+	 * Programmatically set a local flag to the given value, overriding
+	 * an entry in the {@code spring.properties} file (if any).
+	 * @param key the property key
+	 * @param value the associated boolean value
+	 * @since 6.2.6
+	 */
+	public static void setFlag(String key, boolean value) {
+		localProperties.setProperty(key, Boolean.toString(value));
 	}
 
 	/**
@@ -130,4 +141,19 @@ public final class SpringProperties {
 		return Boolean.parseBoolean(getProperty(key));
 	}
 
+	/**
+	 * Retrieve the flag for the given property key, returning {@code null}
+	 * instead of {@code false} in case of no actual flag set.
+	 * @param key the property key
+	 * @return {@code true} if the property is set to the string "true"
+	 * (ignoring case), {@code} false if it is set to any other value,
+	 * {@code null} if it is not set at all
+	 * @since 6.2.6
+	 */
+	@Nullable
+	public static Boolean checkFlag(String key) {
+		String flag = getProperty(key);
+		return (flag != null ? Boolean.valueOf(flag) : null);
+	}
+
 }