Clarify the scope of target in ClassNameGenerator

Closes gh-28517

spring-core/src/main/java/org/springframework/aot/generate/ClassNameGenerator.java

@@ -27,12 +27,13 @@ import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
 /**
- * Generates unique class names that can be used in ahead-of-time generated
- * source code. This class is stateful so the same instance should be used for
- * all name generation. Most commonly the class name generator is obtained via a
- * {@link GenerationContext}.
+ * Generate unique class names based on an optional target {@link Class} and
+ * a feature name. This class is stateful so the same instance should be used
+ * for all name generation. Most commonly the class name generator is obtained
+ * via a {@link GenerationContext}.
  *
  * @author Phillip Webb
+ * @author Stephane Nicoll
  * @since 6.0
  */
 public final class ClassNameGenerator {
@@ -47,10 +48,18 @@ public final class ClassNameGenerator {
 
 
 	/**
-	 * Generate a new class name for the given {@code target} /
-	 * {@code featureName} combination.
-	 * @param target the target of the newly generated class or {@code null} if
-	 * there is not target.
+	 * Generate a unique {@link ClassName} based on the specified {@code target}
+	 * class and {@code featureName}. If a {@code target} is specified, the
+	 * generated class name is a suffixed version of it.
+	 * <p>For instance, a {@code com.example.Demo} target with an
+	 * {@code Initializer} feature name leads to a
+	 * {@code com.example.Demo__Initializer} generated class name. If such a
+	 * feature was already requested for this target, a counter is used to
+	 * ensure uniqueness.
+	 * <p>If there is no target, the {@code featureName} is used to generate the
+	 * class name in the {@value #AOT_PACKAGE} package.
+	 * @param target the class the newly generated class relates to, or
+	 * {@code null} if there is not target
 	 * @param featureName the name of the feature that the generated class
 	 * supports
 	 * @return a unique generated class name
@@ -58,10 +67,11 @@ public final class ClassNameGenerator {
 	public ClassName generateClassName(@Nullable Class<?> target, String featureName) {
 		Assert.hasLength(featureName, "'featureName' must not be empty");
 		featureName = clean(featureName);
-		if(target != null) {
-			return generateSequencedClassName(target.getName().replace("$", "_") + SEPARATOR + StringUtils.capitalize(featureName));
+		if (target != null) {
+			return generateSequencedClassName(target.getName().replace("$", "_")
+					+ SEPARATOR + StringUtils.capitalize(featureName));
 		}
-		return generateSequencedClassName(AOT_PACKAGE+ featureName);
+		return generateSequencedClassName(AOT_PACKAGE + featureName);
 	}
 
 	private String clean(String name) {