Add a findbugs exclusion file.

core/findbugs.xml

@@ -0,0 +1,24 @@
+<!--
+  ~ Copyright 2012 Google Inc.
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~    http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<FindBugsFilter>
+    <Match>
+        <!-- Protos and inner classes are generated by the proto compiler -->
+        <Class name="~org\.bitcoinj\.wallet\.Protos.*"/>
+    </Match>
+
+    <!-- BitCoinJ is not designed to run in an environment with malicious code loaded into the VM -->
+    <Bug category="MALICIOUS_CODE"/>
+</FindBugsFilter>