Document method and field inheritance semantics

See junit-team#3553

documentation/src/docs/asciidoc/user-guide/extensions.adoc

@@ -156,6 +156,15 @@ using the `@Order` annotation. See the <<extensions-registration-programmatic-or
 Extension Registration Order>> tip for `@RegisterExtension` fields for details.
 ====
 
+[TIP]
+.Extension Inheritance
+====
+Extensions registered declaratively via `@ExtendWith` on fields in superclasses will be
+inherited.
+
+See <<extensions-registration-inheritance, Extension Inheritance>> for details.
+====
+
 NOTE: `@ExtendWith` fields may be either `static` or non-static. The documentation on
 <<extensions-registration-programmatic-static-fields, Static Fields>> and
 <<extensions-registration-programmatic-instance-fields, Instance Fields>> for
@@ -196,6 +205,15 @@ extensions to be registered last and _after_ callback extensions to be registere
 relative to other programmatically registered extensions.
 ====
 
+[TIP]
+.Extension Inheritance
+====
+Extensions registered via `@RegisterExtension` or `@ExtendWith` on fields in superclasses
+will be inherited.
+
+See <<extensions-registration-inheritance, Extension Inheritance>> for details.
+====
+
 NOTE: `@RegisterExtension` fields must not be `null` (at evaluation time) but may be
 either `static` or non-static.
 
@@ -304,11 +322,23 @@ support for `TestInfo`, `TestReporter`, etc.).
 [[extensions-registration-inheritance]]
 ==== Extension Inheritance
 
-Registered extensions are inherited within test class hierarchies with top-down
-semantics. Similarly, extensions registered at the class-level are inherited at the
-method-level. Furthermore, a specific extension implementation can only be registered
-once for a given extension context and its parent contexts. Consequently, any attempt to
-register a duplicate extension implementation will be ignored.
+Registered extensions are inherited within test class hierarchies with top-down semantics.
+Similarly, extensions registered at the class-level are inherited at the method-level.
+This applies to all extensions, independent of how they are registered (declaratively or
+programmatically).
+
+This means that extensions registered declaratively via `@ExtendWith` on a superclass will
+be registered before extensions registered declaratively via `@ExtendWith` on a subclass.
+
+Similarly, extensions registered programmatically via `@RegisterExtension` or
+`@ExtendWith` on fields in a superclass will be registered before extensions registered
+programmatically via `@RegisterExtension` or `@ExtendWith` on fields in a subclass, unless
+`@Order` is used to alter that behavior (see <<extensions-registration-programmatic-order,
+Extension Registration Order>> for details).
+
+NOTE: A specific extension implementation can only be registered once for a given
+extension context and its parent contexts. Consequently, any attempt to register a
+duplicate extension implementation will be ignored.
 
 [[extensions-conditions]]
 === Conditional Test Execution
@@ -704,6 +734,8 @@ and fields in a class or interface. Some of these methods search on implemented
 interfaces and within class hierarchies to find annotations. Consult the Javadoc for
 `{AnnotationSupport}` for further details.
 
+NOTE: See also: <<extensions-supported-utilities-search-semantics>>
+
 [[extensions-supported-utilities-classes]]
 ==== Class Support
 
@@ -720,6 +752,8 @@ class, and to find and invoke methods. Some of these methods traverse class hier
 to locate matching methods. Consult the Javadoc for `{ReflectionSupport}` for further
 details.
 
+NOTE: See also: <<extensions-supported-utilities-search-semantics>>
+
 [[extensions-supported-utilities-modifier]]
 ==== Modifier Support
 
@@ -737,6 +771,37 @@ wrapper types, date and time types from the `java.time package`, and some additi
 common Java types such as `File`, `BigDecimal`, `BigInteger`, `Currency`, `Locale`, `URI`,
 `URL`, `UUID`, etc. Consult the Javadoc for `{ConversionSupport}` for further details.
 
+[[extensions-supported-utilities-search-semantics]]
+==== Field and Method Search Semantics
+
+Various methods in `AnnotationSupport` and `ReflectionSupport` employ search algorithms
+that traverse type hierarchies to locate matching fields and methods – for example,
+`AnnotationSupport.findAnnotatedFields(...)`, `ReflectionSupport.findMethods(...)`, etc.
+
+As of JUnit 5.11 (JUnit Platform 1.11), field and method search algorithms adhere to
+standard Java semantics regarding whether a given field or method is visible or overridden
+according to the rules of the Java language.
+
+Prior to JUnit 5.11, the field and method search algorithms applied what we now refer to
+as "legacy semantics". Legacy semantics consider fields and methods to be _hidden_,
+_shadowed_, or _superseded_ by fields and methods in super types (superclasses or
+interfaces) based solely on the field's name or the method's signature, disregarding the
+actual Java language semantics for visibility and the rules that determine if one method
+overrides another method.
+
+Although the JUnit team recommends the use of the standard search semantics, developers
+may optionally revert to the legacy semantics via the
+`junit.platform.reflection.search.useLegacySemantics` JVM system property.
+
+For example, to enable legacy search semantics for fields and methods, you can start your
+JVM with the following system property.
+
+`-Djunit.platform.reflection.search.useLegacySemantics=true`
+
+NOTE: Due to the low-level nature of the feature, the
+`junit.platform.reflection.search.useLegacySemantics` flag can only be set via a JVM
+system property. It cannot be set via a <<running-tests-config-params, configuration
+parameter>>.
 
 [[extensions-execution-order]]
 === Relative Execution Order of User Code and Extensions
@@ -863,31 +928,27 @@ callbacks implemented by `Extension2`. `Extension1` is therefore said to _wrap_
 JUnit Jupiter also guarantees _wrapping_ behavior within class and interface hierarchies
 for user-supplied _lifecycle methods_ (see <<writing-tests-definitions>>).
 
-* `@BeforeAll` methods are inherited from superclasses as long as they are not _hidden_,
-  _overridden_, or _superseded_ (i.e., replaced based on signature only, irrespective of
-  Java's visibility rules). Furthermore, `@BeforeAll` methods from superclasses will be
-  executed **before** `@BeforeAll` methods in subclasses.
+* `@BeforeAll` methods are inherited from superclasses as long as they are not
+  _overridden_. Furthermore, `@BeforeAll` methods from superclasses will be executed
+  **before** `@BeforeAll` methods in subclasses.
 ** Similarly, `@BeforeAll` methods declared in an interface are inherited as long as they
-   are not _hidden_ or _overridden_, and `@BeforeAll` methods from an interface will be
-   executed **before** `@BeforeAll` methods in the class that implements the interface.
-* `@AfterAll` methods are inherited from superclasses as long as they are not _hidden_,
-  _overridden_, or _superseded_ (i.e., replaced based on signature only, irrespective of
-  Java's visibility rules). Furthermore, `@AfterAll` methods from superclasses will be
-  executed **after** `@AfterAll` methods in subclasses.
+   are not _overridden_, and `@BeforeAll` methods from an interface will be executed
+   **before** `@BeforeAll` methods in the class that implements the interface.
+* `@AfterAll` methods are inherited from superclasses as long as they are not
+  _overridden_. Furthermore, `@AfterAll` methods from superclasses will be executed
+  **after** `@AfterAll` methods in subclasses.
 ** Similarly, `@AfterAll` methods declared in an interface are inherited as long as they
-   are not _hidden_ or _overridden_, and `@AfterAll` methods from an interface will be
-   executed **after** `@AfterAll` methods in the class that implements the interface.
+   are not _overridden_, and `@AfterAll` methods from an interface will be executed
+   **after** `@AfterAll` methods in the class that implements the interface.
 * `@BeforeEach` methods are inherited from superclasses as long as they are not
-  _overridden_ or _superseded_ (i.e., replaced based on signature only, irrespective of
-  Java's visibility rules). Furthermore, `@BeforeEach` methods from superclasses will be
-  executed **before** `@BeforeEach` methods in subclasses.
+  _overridden_. Furthermore, `@BeforeEach` methods from superclasses will be executed
+  **before** `@BeforeEach` methods in subclasses.
 ** Similarly, `@BeforeEach` methods declared as interface default methods are inherited as
    long as they are not _overridden_, and `@BeforeEach` default methods will be executed
    **before** `@BeforeEach` methods in the class that implements the interface.
 * `@AfterEach` methods are inherited from superclasses as long as they are not
-  _overridden_ or _superseded_ (i.e., replaced based on signature only, irrespective of
-  Java's visibility rules). Furthermore, `@AfterEach` methods from superclasses will be
-  executed **after** `@AfterEach` methods in subclasses.
+  _overridden_. Furthermore, `@AfterEach` methods from superclasses will be executed
+  **after** `@AfterEach` methods in subclasses.
 ** Similarly, `@AfterEach` methods declared as interface default methods are inherited as
    long as they are not _overridden_, and `@AfterEach` default methods will be executed
    **after** `@AfterEach` methods in the class that implements the interface.