Handle initialization block

Author: aosen-xiong

src/main/java/pico/typecheck/PICONoInitVisitor.java

@@ -1,5 +1,6 @@
 package pico.typecheck;
 
+import static org.checkerframework.javacutil.TreePathUtil.isTopLevelAssignmentInInitializerBlock;
 import static pico.typecheck.PICOAnnotationMirrorHolder.BOTTOM;
 import static pico.typecheck.PICOAnnotationMirrorHolder.IMMUTABLE;
 import static pico.typecheck.PICOAnnotationMirrorHolder.MUTABLE;
@@ -378,6 +379,10 @@ private void checkMutation(Tree node, ExpressionTree variable) {
             // If the enclosing method is constructor, we don't need to check the receiver type
             return;
         }
+        if (isTopLevelAssignmentInInitializerBlock(getCurrentPath())) {
+            // If the assignment is in initializer block, we don't need to check the receiver type
+            return;
+        }
         // Cannot use receiverTree = TreeUtils.getReceiverTree(variable) to determine if it's
         // field assignment or not. Because for field assignment with implicit "this", receiverTree
         // is null but receiverType is non-null. We still need to check this case.