Extend StateBuilder to handle EE from Require-Capability header

With this change, the BundleDescription instance that is returned by the
StateBuilder now also contains the execution environments that are
required by the Require-Capability header, rather than only the
Bundle-RequireExecutionEnvironment header.

Previously, a call to getExecutionEnvironments() would always return an
empty array, if a bundle lacks the Bundle-RequireExecutionEnvironment
header, even though a minimum version is required as a capability.

Resolves eclipse-equinox#643

bundles/org.eclipse.osgi.compatibility.state/src/org/eclipse/osgi/internal/resolver/StateBuilder.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2003, 2020 IBM Corporation and others.
+ * Copyright (c) 2003, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -25,7 +25,9 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
+import java.util.stream.Stream;
 import org.eclipse.osgi.internal.framework.EquinoxContainer;
 import org.eclipse.osgi.internal.framework.FilterImpl;
 import org.eclipse.osgi.internal.messages.Msg;
@@ -47,6 +49,7 @@
 import org.osgi.framework.InvalidSyntaxException;
 import org.osgi.framework.Version;
 import org.osgi.framework.namespace.BundleNamespace;
+import org.osgi.framework.namespace.ExecutionEnvironmentNamespace;
 import org.osgi.framework.namespace.IdentityNamespace;
 import org.osgi.resource.Namespace;
 
@@ -128,7 +131,7 @@ static BundleDescription createBundleDescription(StateImpl state, Dictionary<Str
 		}
 		result.setLocation(location);
 		result.setPlatformFilter(manifest.get(StateImpl.ECLIPSE_PLATFORMFILTER));
-		String[] brees = ManifestElement.getArrayFromList(manifest.get(Constants.BUNDLE_REQUIREDEXECUTIONENVIRONMENT));
+		String[] brees = getDeclaredRequiredEE(manifest);
 		result.setExecutionEnvironments(brees);
 		ManifestElement[] host = ManifestElement.parseHeader(Constants.FRAGMENT_HOST, manifest.get(Constants.FRAGMENT_HOST));
 		if (host != null)
@@ -941,4 +944,58 @@ static GenericDescription createOsgiIdentityCapability(BundleDescription descrip
 		result.setDirectives(directives);
 		return result;
 	}
+
+	/**
+	 * The required execution environment can either be declared via the
+	 * {@link Constants#BUNDLE_REQUIREDEXECUTIONENVIRONMENT} or the
+	 * {@link Constants#REQUIRE_CAPABILITY} header. A manifest is expected to
+	 * have one or the other, but not both. In such case, the former takes
+	 * priority.
+	 * 
+	 * @see {@link #getEEFromFilter(String)}
+	 */
+	private static String[] getDeclaredRequiredEE(Dictionary<String, String> manifest) throws BundleException {
+		@SuppressWarnings("deprecation")
+		String requiredEE = manifest.get(Constants.BUNDLE_REQUIREDEXECUTIONENVIRONMENT);
+		if (requiredEE != null) {
+			return ManifestElement.getArrayFromList(requiredEE);
+		}
+		String requiredCapability = manifest.get(Constants.REQUIRE_CAPABILITY);
+		ManifestElement[] headers = ManifestElement.parseHeader(Constants.REQUIRE_CAPABILITY, requiredCapability);
+		if (headers != null) {
+			return Stream.of(headers) //
+					.map(header -> header.getDirective(Constants.FILTER_DIRECTIVE)) //
+					.map(StateBuilder::getEEFromFilter) //
+					.filter(Objects::nonNull) //
+					.toArray(String[]::new);
+		}
+		return null;
+	}
+
+	/**
+	 * Extracts the execution environment of the given filter specification
+	 * using the environment namespace (e.g. JavaSE) and version attribute
+	 * (e.g. 17). Both values are joined with a '-'. If the filter doesn't
+	 * contain either value or if the filter is otherwise invalid, {@code null}
+	 * is returned.
+	 * 
+	 * @see ExecutionEnvironmentNamespace#EXECUTION_ENVIRONMENT_NAMESPACE
+	 * @see ExecutionEnvironmentNamespace#CAPABILITY_VERSION_ATTRIBUTE
+	 */
+	private static String getEEFromFilter(String filterSpec) {
+		if (filterSpec == null) {
+			return null;
+		}
+		try {
+			FilterImpl filter = FilterImpl.newInstance(filterSpec);
+			String ee = filter.getPrimaryKeyValue(ExecutionEnvironmentNamespace.EXECUTION_ENVIRONMENT_NAMESPACE);
+			String version = filter.getPrimaryKeyValue(ExecutionEnvironmentNamespace.CAPABILITY_VERSION_ATTRIBUTE);
+			if (ee != null && version != null) {
+				return ee + '-' + version;
+			}
+		} catch (InvalidSyntaxException e) {
+			// TODO Special handling needed?
+		}
+		return null;
+	}
 }