[java-decompiler] aligning language level with the main project; bumping Gradle version

GitOrigin-RevId: 068aadf4b64097c66de34ff19134f57083d2ac66

build.gradle

@@ -1,9 +1,9 @@
-// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 apply plugin: 'java'
 
 compileJava {
-  sourceCompatibility '1.8'
+  sourceCompatibility '11'
-  targetCompatibility '1.8'
+  targetCompatibility '11'
 }
 
 sourceSets {
@@ -22,4 +22,4 @@ jar {
   manifest {
     attributes 'Main-Class': 'org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler'
   }
-}
+}

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.0-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.5-all.zip