Build tools update.

https used for maven download
gradle version changed to 4.6
errorprone changed to 2.2.0
findbug replaced by spotbugs

build.gradle

@@ -12,7 +12,8 @@ buildscript {
     }
   }
   dependencies {
-    classpath 'net.ltgt.gradle:gradle-errorprone-plugin:0.0.8'
+    classpath 'net.ltgt.gradle:gradle-errorprone-plugin:0.0.13'
+    classpath 'gradle.plugin.com.github.spotbugs:gradlePlugin:1.6.0'
     classpath 'com.github.jengelman.gradle.plugins:shadow:1.2.3'
     classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.7.3'
   }
@@ -25,7 +26,7 @@ subprojects {
 
     maven { url "https://repo.eclipse.org/content/repositories/paho-releases/" }
     maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
-    maven { url "http://repo.maven.apache.org/maven2" }
+    maven { url "https://repo.maven.apache.org/maven2" }
   }
 
   apply from: new File(rootDir, 'gradle/java.gradle')
@@ -33,10 +34,6 @@ subprojects {
   apply from: new File(rootDir, 'gradle/lint.gradle')
   apply plugin: 'com.jfrog.bintray'
   apply plugin: 'eclipse'
-  apply plugin: 'net.ltgt.errorprone'
-  configurations.errorprone {
-    resolutionStrategy.force 'com.google.errorprone:error_prone_core:2.0.14'
-  }
 
   ext {
     nettyVersion = '4.1.12.Final'
@@ -85,5 +82,5 @@ subprojects {
 }
 
 task wrapper(type: Wrapper) {
-  gradleVersion = '3.3'
+  gradleVersion = '4.6'
 }

gradle/lint.gradle

@@ -1,5 +1,10 @@
 apply plugin: 'checkstyle'
-apply plugin: 'findbugs'
+apply plugin: 'com.github.spotbugs'
+apply plugin: 'net.ltgt.errorprone'
+
+dependencies {
+    errorprone "com.google.errorprone:error_prone_core:2.2.0"
+}
 
 checkstyle {
     configProperties.checkstyleConfigDir = "."
@@ -8,12 +13,8 @@ checkstyle {
     toolVersion = '6.7'
 }
 
-findbugs {
-    toolVersion = '3.0.1'
+spotbugs {
+    toolVersion = '3.1.1'
     ignoreFailures true
     omitVisitors = ['RuntimeExceptionCapture']
 }
-
-tasks.withType(FindBugs) {
-    maxHeapSize = '2g'
-}

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,5 @@
-#Thu Aug 10 18:13:58 CEST 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-bin.zip

gradlew

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 ##############################################################################
 ##
@@ -33,11 +33,11 @@ DEFAULT_JVM_OPTS=""
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
 
-warn ( ) {
+warn () {
     echo "$*"
 }
 
-die ( ) {
+die () {
     echo
     echo "$*"
     echo
@@ -154,11 +154,19 @@ if $cygwin ; then
     esac
 fi
 
-# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
-function splitJvmOpts() {
-    JVM_OPTS=("$@")
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
 }
-eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
-JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+APP_ARGS=$(save "$@")
 
-exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

gradlew.bat

@@ -49,7 +49,6 @@ goto fail
 @rem Get command-line arguments, handling Windows variants
 
 if not "%OS%" == "Windows_NT" goto win9xME_args
-if "%@eval[2+2]" == "4" goto 4NT_args
 
 :win9xME_args
 @rem Slurp the command line arguments.
@@ -60,11 +59,6 @@ set _SKIP=2
 if "x%~1" == "x" goto execute
 
 set CMD_LINE_ARGS=%*
-goto execute
-
-:4NT_args
-@rem Get arguments from the 4NT Shell from JP Software
-set CMD_LINE_ARGS=%$
 
 :execute
 @rem Setup the command line