config: bump guava to 23.6
diff --git a/config/findbugs-exclude.xml b/config/findbugs-exclude.xml
index 186e46b..e9898d1 100644
--- a/config/findbugs-exclude.xml
+++ b/config/findbugs-exclude.xml
@@ -96,4 +96,64 @@
         <Method name="parseJavadocAsDetailNode"/>
         <Bug pattern="BC_UNCONFIRMED_CAST_OF_RETURN_VALUE"/>
     </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.Main"/>
+        <Method name="loadProperties"/>
+        <Bug pattern="NP_NULL_PARAM_DEREF"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.PackageNamesLoader"/>
+        <Method name="processFile"/>
+        <Bug pattern="NP_NULL_PARAM_DEREF"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.PropertyCacheFile"/>
+        <Method name="flushAndCloseOutStream"/>
+        <Bug pattern="NP_NULL_PARAM_DEREF"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.PropertyCacheFile"/>
+        <Method name="load"/>
+        <Bug pattern="NP_NULL_PARAM_DEREF"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.checks.header.AbstractHeaderCheck"/>
+        <Method name="loadHeaderFile"/>
+        <Bug pattern="NP_NULL_PARAM_DEREF"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.ant.CheckstyleAntTask"/>
+        <Method name="createOverridingProperties"/>
+        <Bug pattern="NP_NULL_PARAM_DEREF"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.PropertyCacheFile"/>
+        <Method name="persist"/>
+        <Bug pattern="NP_GUARANTEED_DEREF_ON_EXCEPTION_PATH"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.PropertyCacheFile"/>
+        <Method name="persist"/>
+        <Bug pattern="NP_NULL_PARAM_DEREF"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.checks.TranslationCheck"/>
+        <Method name="getTranslationKeys"/>
+        <Bug pattern="NP_GUARANTEED_DEREF_ON_EXCEPTION_PATH"/>
+    </Match>
+    <Match>
+        <!-- false-positive. See details at https://github.com/checkstyle/checkstyle/pull/5403 -->
+        <Class name="com.puppycrawl.tools.checkstyle.checks.UniquePropertiesCheck"/>
+        <Method name="processFiltered"/>
+        <Bug pattern="NP_GUARANTEED_DEREF_ON_EXCEPTION_PATH"/>
+    </Match>
 </FindBugsFilter>
diff --git a/pom.xml b/pom.xml
index f2e6eae..466a19f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -271,7 +271,7 @@
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
-      <version>23.5-jre</version>
+      <version>23.6-jre</version>
     </dependency>
     <dependency>
       <groupId>org.apache.ant</groupId>