Update to build with JDK 16 and upgrade plugins

Author: mtdowling

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     name: Java ${{ matrix.java }} ${{ matrix.os }}
     strategy:
       matrix:
-        java: [8, 11, 15]
+        java: [8, 11, 16]
         os: [macos-latest, ubuntu-latest, windows-latest]
 
     steps:

build.gradle

@@ -21,9 +21,9 @@ plugins {
     id "signing"
     id "checkstyle"
     id "jacoco"
-    id "com.github.spotbugs" version "4.6.1"
-    id "io.codearte.nexus-staging" version "0.21.0"
-    id "me.champeau.jmh" version "0.6.4"
+    id "com.github.spotbugs" version "4.7.1"
+    id "io.codearte.nexus-staging" version "0.30.0"
+    id "me.champeau.jmh" version "0.6.5"
 }
 
 ext {