[API] Fix dependency tree issue for imgui-java-app

resolve SpaiR#75
resolve SpaiR#127

Removed shadowing for `imgui-java-app.jar` which is published to Maven Central.
Shadow Jar now has a prefix `-all` - for those one who prefer to use raw jars instead dependencies in maven/gradle.

build.gradle

@@ -12,13 +12,6 @@ allprojects {
         mavenCentral()
     }
 
-    tasks.withType(JavaCompile).tap {
-        configureEach {
-            sourceCompatibility = JavaVersion.VERSION_1_8
-            targetCompatibility = JavaVersion.VERSION_1_8
-        }
-    }
-
     tasks.withType(Jar).tap {
         configureEach {
             from(project.rootDir) {

example/build.gradle

@@ -2,8 +2,10 @@ plugins {
     id 'application'
 }
 
-repositories {
-    mavenCentral()
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(8))
+    }
 }
 
 application {

imgui-app/build.gradle

@@ -1,13 +1,15 @@
 plugins {
     id 'java-library'
-    id 'com.github.johnrengelman.shadow' version '7.0.0'
+    id 'com.github.johnrengelman.shadow' version '7.1.2'
     id 'checkstyle'
     id 'maven-publish'
     id 'signing'
 }
 
-repositories {
-    mavenCentral()
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(8))
+    }
 }
 
 dependencies {
@@ -44,7 +46,6 @@ jar {
 
 shadowJar {
     with jar
-    archiveClassifier.set(null)
 }
 
 apply from: "$rootDir/publish.gradle"

imgui-binding-natives/build.gradle

@@ -4,6 +4,12 @@ plugins {
     id 'signing'
 }
 
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(8))
+    }
+}
+
 def packageName = 'imgui-java-natives-linux'
 def packageDesc = 'Native binaries for imgui-java binding for Linux'
 def moduleName = 'imgui.natives.linux'

imgui-binding/build.gradle

@@ -7,6 +7,12 @@ plugins {
     id 'signing'
 }
 
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(8))
+    }
+}
+
 dependencies {
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.5.2'
     testImplementation 'org.junit.jupiter:junit-jupiter-engine:5.5.2'

imgui-lwjgl3/build.gradle

@@ -5,6 +5,12 @@ plugins {
     id 'signing'
 }
 
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(8))
+    }
+}
+
 dependencies {
     implementation platform("org.lwjgl:lwjgl-bom:$lwjglVersion")