Revert "Build: Added java toolchain to build.gradle"

This reverts commit 1fe0761.

Author: jyemin

build.gradle

@@ -27,7 +27,7 @@ buildscript {
         classpath 'com.netflix.nebula:gradle-extra-configurations-plugin:3.0.3'
         classpath "gradle.plugin.com.github.spotbugs.snom:spotbugs-gradle-plugin:4.5.0"
         classpath 'biz.aQute.bnd:biz.aQute.bnd.gradle:5.1.2'
-
+        
         // Scala plugins
         classpath "com.adtran:scala-multiversion-plugin:1.0.36"
         classpath "com.diffplug.spotless:spotless-plugin-gradle:3.27.1"
@@ -61,21 +61,6 @@ def javaMainProjects = javaProjects.findAll { !['util'].contains(it.name) }
 def javaCodeCheckedProjects = javaMainProjects.findAll { !['driver-benchmarks', 'driver-workload-executor'].contains(it.name) }
 def javaAndScalaTestedProjects = javaCodeCheckedProjects + scalaProjects
 
-tasks.withType(JavaCompile) {
-    options.encoding = "UTF-8"
-    options.release.set(8)
-}
-
-final Integer DEFAULT_JDK_VERSION = 11
-
-tasks.withType(Test) {
-    def javaVersion = (findProperty("jdkVersion") ?: DEFAULT_JDK_VERSION.toString()).toInteger()
-    logger.info("Running tests using JDK$javaVersion")
-    javaLauncher.set(javaToolchains.launcherFor {
-        languageVersion = JavaLanguageVersion.of(javaVersion)
-    })
-}
-
 configure(coreProjects) {
     apply plugin: 'idea'
 
@@ -97,11 +82,8 @@ configure(coreProjects) {
 configure(javaProjects) {
     apply plugin: 'java-library'
 
-    java {
-        toolchain {
-            languageVersion = JavaLanguageVersion.of(DEFAULT_JDK_VERSION)
-        }
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 
     sourceSets {
         main {
@@ -112,7 +94,6 @@ configure(javaProjects) {
     tasks.withType(GenerateModuleMetadata) {
         enabled = false
     }
-
 }
 
 configure(scalaProjects) {
@@ -123,11 +104,8 @@ configure(scalaProjects) {
 
     group = 'org.mongodb.scala'
 
-    java {
-        toolchain {
-            languageVersion = JavaLanguageVersion.of(DEFAULT_JDK_VERSION)
-        }
-    }
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
 
     dependencies {
         compile ('org.scala-lang:scala-library:%scala-version%')
@@ -175,7 +153,7 @@ configure(scalaProjects) {
 configure(javaMainProjects) {
     apply plugin: 'nebula.optional-base'
     apply plugin: 'java-library'
-
+    
     dependencies {
         compileOnly 'com.google.code.findbugs:jsr305:1.3.9'
         api 'org.slf4j:slf4j-api:1.7.6', optional
@@ -352,6 +330,19 @@ configure(javaCodeCheckedProjects) {
     spotbugsTest {
         enabled = false
     }
+
+    tasks.withType(Test) {
+        def jdkHome = findProperty("jdkHome")
+        if (jdkHome) {
+            def javaExecutablesPath = new File(jdkHome, 'bin')
+            def javaExecutables = [:].withDefault { execName ->
+                def executable = new File(javaExecutablesPath, execName)
+                assert executable.exists() : "There is no ${execName} executable in ${javaExecutablesPath}"
+                executable
+            }
+            executable = javaExecutables.java
+        }
+    }
 }
 
 def getGitVersion() {
@@ -366,3 +357,15 @@ def getGitVersion() {
 apply from: 'gradle/publish.gradle'
 apply from: 'gradle/deploy.gradle'
 apply from: 'gradle/javadoc.gradle'
+
+//////////////////////////////////////////
+// Root project configuration           //
+//////////////////////////////////////////
+
+if (!JavaVersion.current().isJava9Compatible()) {
+    throw new GradleException("""
+        | ERROR:
+        | JDK ${JavaVersion.VERSION_1_9.getMajorVersion()} is required to build the driver: You are using JDK ${JavaVersion.current().getMajorVersion()}.
+        |""".stripMargin()
+    )
+}

driver-core/src/main/com/mongodb/MongoCredential.java

@@ -293,7 +293,7 @@ public static MongoCredential createPlainCredential(final String userName, final
      * {@code "JAVA_SUBJECT"} with the value of a {@code Subject} instance.
      * <p>
      * To override the properties of the {@link javax.security.sasl.SaslClient} with which the authentication executes, add a mechanism
-     * property with the name {@code "JAVA_SASL_CLIENT_PROPERTIES"} with the value of a {@code Map<String, Object>} instance containing the
+     * property with the name {@code "JAVA_SASL_CLIENT_PROPERTIES"} with the value of a {@code Map<String, Object} instance containing the
      * necessary properties.  This can be useful if the application is customizing the default
      * {@link javax.security.sasl.SaslClientFactory}.
      *