build(android): load gradle conditionally

aMarCruz#22

Author: vasylnahuliak

android/build.gradle

@@ -14,12 +14,18 @@ def _targetSdkVersion   = safeExtGet('targetSdkVersion', 28)
 def _minSdkVersion      = safeExtGet('minSdkVersion', 16)
 
 buildscript {
-    repositories {
-        google()
-        mavenCentral()
-    }
-    dependencies {
-        classpath 'com.android.tools.build:gradle:3.4.1'
+    // The Android Gradle plugin is only required when opening the android folder stand-alone.
+    // This avoids unnecessary downloads and potential conflicts when the library is included as a
+    // module dependency in an application project.
+    if (project == rootProject) {
+        repositories {
+            google()
+            mavenCentral()
+        }
+
+        dependencies {
+            classpath 'com.android.tools.build:gradle:3.4.1'
+        }
     }
 }