method hierarchy: search functional expressions by current method only (IDEA-124320); navigation (IDEA-124319)

java/java-impl/src/com/intellij/ide/hierarchy/method/MethodHierarchyNodeDescriptor.java

@@ -52,7 +52,7 @@ public final class MethodHierarchyNodeDescriptor extends HierarchyNodeDescriptor
     myTreeStructure = treeStructure;
   }
 
-  private PsiMethod getMethod(final PsiClass aClass, final boolean checkBases) {
+  PsiMethod getMethod(final PsiClass aClass, final boolean checkBases) {
     return MethodHierarchyUtil.findBaseMethodInClass(myTreeStructure.getBaseMethod(), aClass, checkBases);
   }
 

java/java-impl/src/com/intellij/ide/hierarchy/method/MethodHierarchyTreeStructure.java

@@ -172,13 +172,16 @@ public final class MethodHierarchyTreeStructure extends HierarchyTreeStructure {
       descriptors.add(d);
     }
 
-    FunctionalExpressionSearch.search(getBaseMethod()).forEach(new Processor<PsiFunctionalExpression>() {
-      @Override
-      public boolean process(PsiFunctionalExpression expression) {
-        descriptors.add(new MethodHierarchyNodeDescriptor(myProject, descriptor, expression, false, MethodHierarchyTreeStructure.this));
-        return true;
-      }
-    });
+    final PsiMethod existingMethod = ((MethodHierarchyNodeDescriptor)descriptor).getMethod(psiClass, false);
+    if (existingMethod != null) {
+      FunctionalExpressionSearch.search(existingMethod).forEach(new Processor<PsiFunctionalExpression>() {
+        @Override
+        public boolean process(PsiFunctionalExpression expression) {
+          descriptors.add(new MethodHierarchyNodeDescriptor(myProject, descriptor, expression, false, MethodHierarchyTreeStructure.this));
+          return true;
+        }
+      });
+    }
 
     return descriptors.toArray(new HierarchyNodeDescriptor[descriptors.size()]);
   }

java/java-psi-api/src/com/intellij/psi/PsiFunctionalExpression.java

@@ -18,7 +18,7 @@ package com.intellij.psi;
 import com.intellij.openapi.util.Iconable;
 import org.jetbrains.annotations.Nullable;
 
-public interface PsiFunctionalExpression extends PsiExpression, Iconable {
+public interface PsiFunctionalExpression extends PsiExpression, Iconable, NavigatablePsiElement {
   /**
    * @return SAM type the lambda expression corresponds to
    *         null when no SAM type could be found