feat(databind): add typed collection support for choice groups

.claude/rules/metaschema-authoring.md

@@ -72,8 +72,9 @@ The following packages contain binding classes derived from Metaschema modules:
 
 | Package | Source Metaschema | Bootstrap POM |
 |---------|------------------|---------------|
-| `databind/src/main/java/gov/nist/secauto/metaschema/databind/config/binding/` | `databind/src/main/metaschema/metaschema-bindings.yaml` | `databind/pom-bootstrap.xml` |
-| `metaschema-testing/src/main/java/gov/nist/secauto/metaschema/model/testing/testsuite/` | `metaschema-testing/src/main/metaschema/unit-tests.yaml` | `metaschema-testing/pom-bootstrap.xml` |
+| `databind/.../config/binding/` | `databind/src/main/metaschema/metaschema-bindings.yaml` | `databind/pom-bootstrap-config.xml` |
+| `databind/.../model/metaschema/binding/` | `core/metaschema/schema/metaschema/metaschema-module-metaschema.xml` | `databind/pom-bootstrap-model.xml` |
+| `metaschema-testing/.../testsuite/` | `metaschema-testing/src/main/metaschema/unit-tests.yaml` | `metaschema-testing/pom-bootstrap.xml` |
 
 ### CRITICAL: Never Manually Edit Generated Binding Classes
 
@@ -93,7 +94,7 @@ When you need to modify a generated binding class:
 - The Metaschema module is the authoritative source for the data model
 
 **Red flags that you're about to make a mistake:**
-- Opening a file in `.../config/binding/` or `.../testsuite/` for editing
+- Opening a file in `.../config/binding/`, `.../model/metaschema/binding/`, or `.../testsuite/` for editing
 - Adding fields, methods, or annotations directly to these classes
 - Copying code patterns from these files to create new bindings manually
 

CLAUDE.md

@@ -109,20 +109,28 @@ Generated sources are placed in `target/generated-sources/` and excluded from st
 
 ### Bootstrap Binding Classes
 
-The `metaschema-testing` module contains pre-generated binding classes that cannot be generated during the normal build due to circular dependencies (metaschema-maven-plugin → metaschema-schema-generator → metaschema-testing).
+Several modules contain pre-generated binding classes that cannot be generated during the normal build due to circular dependencies. These classes must be regenerated manually when their source Metaschema modules change.
 
-To regenerate these classes when the test suite Metaschema module changes:
+| Module | Bootstrap POM | Generated Package | Source Metaschema |
+|--------|--------------|-------------------|-------------------|
+| metaschema-testing | `metaschema-testing/pom-bootstrap.xml` | `...model.testing.testsuite` | `unit-tests.yaml` |
+| databind | `databind/pom-bootstrap-config.xml` | `...databind.config.binding` | `metaschema-bindings.yaml` |
+| databind | `databind/pom-bootstrap-model.xml` | `...databind.model.metaschema.binding` | `metaschema-module-metaschema.xml` |
+
+To regenerate binding classes:
 
 ```bash
-# Generate binding classes using bootstrap POM
-mvn -f metaschema-testing/pom-bootstrap.xml generate-sources
+# First ensure the project is built
+mvn install -DskipTests
 
-# Copy to source directory
-cp -r metaschema-testing/target/generated-sources/metaschema/gov/nist/secauto/metaschema/model/testing/testsuite/* \
-      metaschema-testing/src/main/java/gov/nist/secauto/metaschema/model/testing/testsuite/
+# Generate binding classes using bootstrap POM (choose the appropriate module)
+# Each bootstrap POM generates classes directly into src/main/java
+mvn -f metaschema-testing/pom-bootstrap.xml generate-sources
+mvn -f databind/pom-bootstrap-config.xml generate-sources
+mvn -f databind/pom-bootstrap-model.xml generate-sources
 ```
 
-See `metaschema-testing/README.md` for details.
+See the README.md files in each module for detailed instructions.
 
 ### Metaschema Module Authoring
 

databind-metaschema/pom.xml

@@ -149,30 +149,6 @@
 				<artifactId>metaschema-maven-plugin</artifactId>
 				<version>${project.version}</version>
 				<executions>
-					<execution>
-						<id>metaschema-codegen</id>
-						<phase>generate-sources</phase>
-						<goals>
-							<goal>generate-sources</goal>
-						</goals>
-						<configuration>
-							<metaschemaDir>
-								${project.build.directory}/generated-resources/metaschema-sources</metaschemaDir>
-							<outputDirectory>
-								${project.build.directory}/generated-sources/metaschema</outputDirectory>
-							<configs>
-								<config>
-									${project.basedir}/src/main/metaschema-bindings/metaschema-metaschema-bindings.xml</config>
-							</configs>
-							<includes>
-								<include>metaschema-module-metaschema.xml</include>
-							</includes>
-							<constraints>
-								<constraint>
-									${project.build.directory}/generated-resources/metaschema-sources/metaschema-module-constraints.xml</constraint>
-							</constraints>
-						</configuration>
-					</execution>
 					<execution>
 						<id>metaschema-xml-schema</id>
 						<phase>generate-sources</phase>

databind/README.md

@@ -0,0 +1,72 @@
+# Metaschema Java Data Binding and Code Generation
+
+This module provides the data binding framework and code generation capabilities for Metaschema.
+
+## Bootstrap Binding Classes
+
+This module contains two sets of pre-generated binding classes that are checked into source control due to circular dependency constraints with the `metaschema-maven-plugin`.
+
+### Config Binding Classes
+
+Package: `gov.nist.secauto.metaschema.databind.config.binding`
+
+These classes are generated from the binding configuration schema (`src/main/metaschema/metaschema-bindings.yaml`) and are used to parse binding configuration files.
+
+**Regeneration:**
+
+```bash
+# From the project root - first ensure the project is built
+mvn install -DskipTests
+
+# Generate binding classes
+mvn -f databind/pom-bootstrap-config.xml generate-sources
+
+# Verify the build still passes
+mvn install -PCI -Prelease
+```
+
+### Model Binding Classes
+
+Package: `gov.nist.secauto.metaschema.databind.model.metaschema.binding`
+
+These classes are generated from the core Metaschema module (`core/metaschema/schema/metaschema/metaschema-module-metaschema.xml`) and are used for parsing Metaschema module definitions.
+
+**Regeneration:**
+
+```bash
+# From the project root - first ensure the project is built
+mvn install -DskipTests
+
+# Generate binding classes
+mvn -f databind/pom-bootstrap-model.xml generate-sources
+
+# Verify the build still passes
+mvn install -PCI -Prelease
+```
+
+## Binding Configurations
+
+### Config Bindings
+
+**File:** `src/main/metaschema-bindings/metaschema-config-bindings.xml`
+
+Customizes the generated config binding classes.
+
+### Model Bindings
+
+**File:** `src/main/metaschema-bindings/metaschema-model-bindings.xml`
+
+Customizes the generated model binding classes:
+
+- Maps the Metaschema namespace to `gov.nist.secauto.metaschema.databind.model.metaschema.binding`
+- Renames `group-as` to `GroupingAs` (avoids Java keyword conflict)
+- Adds interface implementations to constraint classes (e.g., `IModelConstraintsBase`)
+- Adds interface implementations to inline definitions for typed collections
+
+## Related Bootstrap POMs
+
+| Bootstrap POM | Generated Package | Source Metaschema |
+|--------------|-------------------|-------------------|
+| `databind/pom-bootstrap-config.xml` | `...databind.config.binding` | `metaschema-bindings.yaml` |
+| `databind/pom-bootstrap-model.xml` | `...databind.model.metaschema.binding` | `metaschema-module-metaschema.xml` |
+| `metaschema-testing/pom-bootstrap.xml` | `...model.testing.testsuite` | `unit-tests.yaml` |

databind/pom-bootstrap.xml → databind/pom-bootstrap-config.xml

@@ -3,7 +3,7 @@
   This POM is used to regenerate the metaschema-bindings binding classes.
   It is NOT part of the normal build due to circular dependencies.
 
-  Usage: mvn -f databind/pom-bootstrap.xml generate-sources
+  Usage: mvn -f databind/pom-bootstrap-config.xml generate-sources
 
   This will:
   1. Delete existing generated classes in the config/binding package
@@ -76,7 +76,7 @@
 							<metaschemaDir>${project.basedir}/src/main/metaschema</metaschemaDir>
 							<outputDirectory>${project.basedir}/src/main/java</outputDirectory>
 							<configs>
-								<config>${project.basedir}/src/main/metaschema-bindings/metaschema-binding-bindings.xml</config>
+								<config>${project.basedir}/src/main/metaschema-bindings/metaschema-config-bindings.xml</config>
 							</configs>
 							<includes>
 								<include>metaschema-bindings.yaml</include>

databind-metaschema/pom-bootstrap.xml → databind/pom-bootstrap-model.xml

@@ -3,11 +3,11 @@
   This POM is used to regenerate the Metaschema model binding classes.
   It is NOT part of the normal build due to circular dependencies.
 
-  Usage: mvn -f databind-metaschema/pom-bootstrap.xml generate-sources
+  Usage: mvn -f databind/pom-bootstrap-model.xml generate-sources
 
   This will:
-  1. Delete existing generated classes in databind's model/metaschema/binding package
-  2. Generate new binding classes directly into databind/src/main/java
+  1. Delete existing generated classes in the model/metaschema/binding package
+  2. Generate new binding classes directly into src/main/java
 
   IMPORTANT: Build the project first to ensure the code generator is up to date:
   mvn install -DskipTests
@@ -19,36 +19,39 @@
 		<artifactId>metaschema-framework</artifactId>
 		<version>3.0.0-SNAPSHOT</version>
 	</parent>
-	<artifactId>metaschema-databind-modules-bootstrap</artifactId>
+	<artifactId>metaschema-databind-model-bootstrap</artifactId>
 	<packaging>pom</packaging>
-	<name>Metaschema Modules - Binding Class Generator</name>
+	<name>Metaschema Databind - Model Binding Class Generator</name>
 	<description>Standalone POM for regenerating Metaschema model binding classes.</description>
 
 	<properties>
-		<!-- For testing: generate to target directory first, then compare with existing -->
-		<output.dir>${project.build.directory}/generated-sources/metaschema</output.dir>
-		<binding.package.dir>${project.basedir}/../databind/src/main/java/gov/nist/secauto/metaschema/databind/model/metaschema/binding</binding.package.dir>
+		<binding.package.dir>${project.basedir}/src/main/java/gov/nist/secauto/metaschema/databind/model/metaschema/binding</binding.package.dir>
 		<stale.file.dir>${project.build.directory}/metaschema</stale.file.dir>
 		<metaschema.sources.dir>${project.basedir}/../core/metaschema/schema/metaschema</metaschema.sources.dir>
 	</properties>
 
 	<build>
 		<plugins>
-			<!-- Step 1: Clean stale file to force regeneration -->
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-clean-plugin</artifactId>
 				<executions>
 					<execution>
-						<id>clean-stale-file</id>
+						<id>clean-generated-sources</id>
 						<phase>initialize</phase>
 						<goals>
 							<goal>clean</goal>
 						</goals>
 						<configuration>
 							<excludeDefaultDirectories>true</excludeDefaultDirectories>
 							<filesets>
-								<!-- Clean the stale file to force regeneration -->
+								<fileset>
+									<directory>${binding.package.dir}</directory>
+									<includes>
+										<include>**/*.java</include>
+									</includes>
+								</fileset>
+								<!-- Also clean the stale file to force regeneration -->
 								<fileset>
 									<directory>${stale.file.dir}</directory>
 									<includes>
@@ -60,7 +63,6 @@
 					</execution>
 				</executions>
 			</plugin>
-			<!-- Step 2: Generate binding classes to test directory for comparison -->
 			<plugin>
 				<groupId>${project.groupId}</groupId>
 				<artifactId>metaschema-maven-plugin</artifactId>
@@ -74,7 +76,7 @@
 						</goals>
 						<configuration>
 							<metaschemaDir>${metaschema.sources.dir}</metaschemaDir>
-							<outputDirectory>${output.dir}</outputDirectory>
+							<outputDirectory>${project.basedir}/src/main/java</outputDirectory>
 							<configs>
 								<config>${project.basedir}/src/main/metaschema-bindings/metaschema-model-bindings.xml</config>
 							</configs>