add additionalJavaArguments (#98)

build.gradle

@@ -69,6 +69,7 @@ propertyDefaultIfUnset("includeMCVersionJar", false)
 propertyDefaultIfUnset("autoUpdateBuildScript", false)
 propertyDefaultIfUnset("modArchivesBaseName", project.modId)
 propertyDefaultIfUnsetWithEnvVar("developmentEnvironmentUserName", "Developer", "DEV_USERNAME")
+propertyDefaultIfUnset("additionalJavaArguments", "")
 propertyDefaultIfUnset("enableJava17RunTasks", false)
 propertyDefaultIfUnset("generateGradleTokenClass", "")
 propertyDefaultIfUnset("gradleTokenModId", "")
@@ -382,6 +383,10 @@ minecraft {
         ])
     }
 
+    if (additionalJavaArguments.size() != 0) {
+        extraRunJvmArguments.addAll(additionalJavaArguments.split(';'))
+    }
+
     if (enableJava17RunTasks.toBoolean()) {
         lwjgl3Version = "3.3.2"
     }

gradle.properties

@@ -27,6 +27,11 @@ minecraftVersion = 1.12.2
 # Alternatively this can be set with the 'DEV_USERNAME' environment variable.
 developmentEnvironmentUserName = Developer
 
+# Additional arguments applied to the JVM when launching minecraft
+# Syntax: -arg1=value1;-arg2=value2;...
+# Example value: -Dmixin.debug.verify=true;-XX:+UnlockExperimentalVMOptions
+additionalJavaArguments = 
+
 # Enables using modern java syntax (up to version 17) via Jabel, while still targeting JVM 8.
 # See https://github.com/bsideup/jabel for details on how this works.
 # Using this requires that you use a Java 17 JDK for development.