Clarify API around CBuildConfiguration.getBuildDirectory as @nooverride

NewAndNoteworthy/CHANGELOG-API.md

@@ -165,6 +165,12 @@ Added methods that can be used to check/fix the Launch Target name:
 - Added class:
   - org.eclipse.launchbar.core.target.LaunchTargetUtils
 
+#### org.eclipse.cdt.core.build.CBuildConfiguration.getBuildDirectory() should not be overridden
+
+The `@nooverride` flag was added to `CBuildConfiguration.getBuildDirectory`.
+Extenders should only be overridding `getBuildDirectoryURI` which is part of the `ICBuildConfiguration2` API.
+`getBuildDirectory` is a convenience method to convert URI into Path.
+
 #### org.eclipse.cdt.cmake.core.properties refactored
 
 A significant simplification to the CMake build properties was completed, this included removing some API that was not used.

core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/build/CBuildConfiguration.java

@@ -325,6 +325,13 @@ public abstract class CBuildConfiguration extends PlatformObject implements ICBu
 		return getBuildContainer().getLocationURI();
 	}
 
+	/**
+	 * Convenience method to convert getBuildDirectoryURI() to a Path
+	 * <p>
+	 * @apiNote This method used to be overridable, but it leads to unclear semantics for extenders.
+	 * Extenders looking to change the build directory should only override {@link #getBuildDirectoryURI()}
+	 * @nooverride This method is not intended to be re-implemented or extended by clients.
+	 */
 	public Path getBuildDirectory() throws CoreException {
 		return Paths.get(getBuildDirectoryURI());
 	}