Revert: Add gradle-versions-plugin (#782)

Since we're using dependantbot.

Author: tokuhirom

Diff for: CONTRIBUTING.md

@@ -13,67 +13,3 @@ source projects you are aware of. It will be amazing if you could help us by doi
 When you are sending a pull request and it's a non-trivial change beyond fixing typos, please make sure to sign
 [the ICLA (individual contributor license agreement)](https://cla-assistant.io/line/line-bot-sdk-java). Please
 [contact us](mailto:dl_oss_dev@linecorp.com) if you need the CCLA (corporate contributor license agreement).
-
-# Detect outdated dependencies
-
-Run `./gradlew dependencyUpdates -Drevision=release` checks dependency list 
-and reports outdated dependencies excepts SpringManaged dependency.
-
-## ./gradlew dependencyUpdates example
-```
-% ./gradlew dependencyUpdates -Drevision=release
-Download https://plugins.gradle.org/m2/org/springframework/boot/spring-boot-gradle-plugin/maven-metadata.xml
-
-> Task :dependencyUpdates
-
-------------------------------------------------------------
-: Project Dependency Updates (report to plain text file)
-------------------------------------------------------------
-
-The following dependencies are using the latest release version:
- - com.github.ben-manes:gradle-versions-plugin:0.20.0
- - com.github.stefanbirkner:system-rules:1.18.0
- - com.squareup.okhttp3:logging-interceptor:3.11.0
- - com.squareup.okhttp3:mockwebserver:3.11.0
- - com.squareup.retrofit2:converter-jackson:2.4.0
- - com.squareup.retrofit2:retrofit:2.4.0
- - io.franzbecker:gradle-lombok:1.14
- - io.spring.gradle:dependency-management-plugin:1.0.6.RELEASE
- - org.projectlombok:lombok:1.18.2
- - org.slf4j:slf4j-api:1.7.25
-
-The following dependencies have later release versions:
- - com.google.guava:guava [25.1-jre -> 26.0-jre]
-     https://github.com/google/guava
- - gradle.plugin.com.github.spotbugs:spotbugs-gradle-plugin [1.6.2 -> 1.6.3]
- - gradle.plugin.com.gorylenko.gradle-git-properties:gradle-git-properties [1.4.17 -> 1.5.2]
- - io.spring.gradle:propdeps-plugin [0.0.9.RELEASE -> 0.0.10.RELEASE]
- - org.jetbrains.kotlin:kotlin-gradle-plugin [1.2.61 -> 1.2.70]
-     https://kotlinlang.org/
- - org.jetbrains.kotlin:kotlin-scripting-compiler-embeddable [1.2.61 -> 1.2.70]
-     https://kotlinlang.org/
- - org.jetbrains.kotlin:kotlin-stdlib-jdk8 [1.2.61 -> 1.2.70]
-     https://kotlinlang.org/
-
-Failed to determine the latest version for the following dependencies (use --info for details):
- - com.fasterxml.jackson.core:jackson-annotations
- - com.fasterxml.jackson.core:jackson-core
- - com.fasterxml.jackson.core:jackson-databind
- - com.fasterxml.jackson.datatype:jackson-datatype-jsr310
- - com.fasterxml.jackson.module:jackson-module-parameter-names
- - javax.servlet:javax.servlet-api
- - javax.validation:validation-api
- - org.hibernate:hibernate-validator
- - org.springframework.boot:spring-boot-autoconfigure
- - org.springframework.boot:spring-boot-configuration-processor
- - org.springframework.boot:spring-boot-gradle-plugin
- - org.springframework.boot:spring-boot-starter-logging
- - org.springframework.boot:spring-boot-starter-test
- - org.springframework.boot:spring-boot-starter-web
-
-Gradle updates:
- - Gradle: [4.8 -> 4.10.1]
-
-Generated report file build/dependencyUpdates/report.txt
-```
-

Diff for: build.gradle

@@ -32,7 +32,6 @@ buildscript {
         maven { url 'https://repo.spring.io/plugins-release' }
     }
     dependencies {
-        classpath 'com.github.ben-manes:gradle-versions-plugin:0.42.0'
         classpath 'com.puppycrawl.tools:checkstyle:10.3.1'
         classpath "com.github.spotbugs.snom:spotbugs-gradle-plugin:5.0.9"
         classpath 'io.franzbecker:gradle-lombok:5.0.0'
@@ -44,7 +43,6 @@ buildscript {
 
 apply plugin: 'idea'
 apply plugin: 'jacoco'
-apply plugin: 'com.github.ben-manes.versions'
 
 group = 'com.linecorp.bot'
 version = '4.10.0'
@@ -121,32 +119,6 @@ subprojects {
     compileJava.dependsOn(processResources)
     // http://docs.spring.io/spring-boot/docs/current/reference/html/configuration-metadata.html#configuration-metadata-annotation-processor
 
-    def springManagedModules = [
-        'org.springframework',
-        'com.fasterxml.jackson',
-        'javax.validation',
-        'org.hibernate',
-        'javax.servlet'
-    ];
-    dependencyUpdates.resolutionStrategy {
-        componentSelection { rules ->
-            rules.all { ComponentSelection selection ->
-                boolean springManaged = springManagedModules.any { module ->
-                    selection.candidate.group.startsWith(module)
-                }
-                if (springManaged) {
-                    selection.reject('Spring Managed')
-                }
-                boolean rejected = ['alpha', 'beta', 'rc', 'cr', 'm'].any { qualifier ->
-                    selection.candidate.version ==~ /(?i).*[.-]${qualifier}\d*[.\d-]*/
-                }
-                if (rejected) {
-                    selection.reject('Release candidate')
-                }
-            }
-        }
-    }
-
     jar {
         manifest {
             attributes 'Implementation-Title': project.name,