PY-8427 Behave BDD support

PY-4186 Lettuce BDD tool support

Initial extension point impl

python/openapi/src/com/jetbrains/python/packaging/PyPackageManager.java

@@ -17,6 +17,7 @@ package com.jetbrains.python.packaging;
 
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.projectRoots.Sdk;
+import org.jetbrains.annotations.Nullable;
 
 import java.awt.*;
 
@@ -39,6 +40,7 @@ public abstract class PyPackageManager {
   public abstract void showInstallationError(Project project, String title, String description);
   public abstract void showInstallationError(Component owner, String title, String description);
   public abstract void refresh();
+  @Nullable
   public abstract PyPackage findPackage(String name) throws PyExternalProcessException;
 
 }

python/openapi/src/com/jetbrains/python/packaging/PyPackageManagers.java

@@ -18,6 +18,7 @@ package com.jetbrains.python.packaging;
 import com.intellij.openapi.components.ServiceManager;
 import com.intellij.openapi.module.Module;
 import com.intellij.openapi.projectRoots.Sdk;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
@@ -26,10 +27,13 @@ import java.util.List;
  * @author yole
  */
 public abstract class PyPackageManagers {
+
+  @NotNull
   public static PyPackageManagers getInstance() {
     return ServiceManager.getService(PyPackageManagers.class);
   }
 
+  @NotNull
   public abstract PyPackageManager forSdk(Sdk sdk);
 
   /**

python/psi-api/src/com/jetbrains/python/psi/PyFile.java

@@ -27,6 +27,7 @@ public interface PyFile extends PyElement, PsiFile, PyDocStringOwner, ScopeOwner
 
   List<PyClass> getTopLevelClasses();
 
+  @NotNull
   List<PyFunction> getTopLevelFunctions();
 
   List<PyTargetExpression> getTopLevelAttributes();

python/psi-api/src/com/jetbrains/python/psi/impl/PyPsiUtils.java

@@ -236,6 +236,7 @@ public class PyPsiUtils {
     }
   }
 
+  @NotNull
   static <T, U extends PsiElement> List<T> collectStubChildren(U e,
                                                                final StubElement<U> stub, final IElementType elementType,
                                                                final Class<T> itemClass) {

python/src/com/jetbrains/python/packaging/PyPackageManagerImpl.java

@@ -603,6 +603,7 @@ public class PyPackageManagerImpl extends PyPackageManager {
     return packages != null ? findPackageByName(name, packages) : null;
   }
 
+  @Nullable
   private static PyPackage findPackageByName(String name, List<PyPackage> packages) {
     for (PyPackage pkg : packages) {
       if (name.equalsIgnoreCase(pkg.getName())) {

python/src/com/jetbrains/python/packaging/PyPackageManagersImpl.java

@@ -17,6 +17,7 @@ package com.jetbrains.python.packaging;
 
 import com.intellij.openapi.module.Module;
 import com.intellij.openapi.projectRoots.Sdk;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.HashMap;
@@ -29,6 +30,7 @@ import java.util.Map;
 public class PyPackageManagersImpl extends PyPackageManagers {
   private final Map<String, PyPackageManagerImpl> myInstances = new HashMap<String, PyPackageManagerImpl>();
 
+  @NotNull
   @Override
   public synchronized PyPackageManager forSdk(Sdk sdk) {
     final String name = sdk.getName();

python/src/com/jetbrains/python/psi/impl/PyFileImpl.java

@@ -419,6 +419,7 @@ public class PyFileImpl extends PsiFileBase implements PyFile, PyExpression {
     return PyPsiUtils.collectStubChildren(this, this.getStub(), PyElementTypes.CLASS_DECLARATION, PyClass.class);
   }
 
+  @NotNull
   @Override
   public List<PyFunction> getTopLevelFunctions() {
     return PyPsiUtils.collectStubChildren(this, this.getStub(), PyElementTypes.FUNCTION_DECLARATION, PyFunction.class);