For anyone who doesn't want to search for the LWJGL values that are causing ForgeGradle builds to fail... Here is mine.

dev.json

{
  "id": "@minecraft_version@-@project@@version@",
  "time": "@timestamp@",
  "releaseTime": "1960-01-01T00:00:00-0700",
  "type": "release",
  "minecraftArguments": "--version FML_DEV --tweakClass cpw.mods.fml.common.launcher.FMLTweaker",
  "libraries": [
    {
      "name": "net.minecraft:launchwrapper:1.9",
      "comment" : "Important for FML, we add this"
    },
    {
      "name": "org.ow2.asm:asm-debug-all:4.1",
      "children" : ["sources"],
      "url" : "http://repo.maven.apache.org/maven2",
      "comment" : "Important for FML, we add this"
    },
    {
      "name": "org.scala-lang:scala-library:2.10.2",
      "children" : ["sources"],
      "url" : "http://repo.maven.apache.org/maven2",
      "comment" : "Important for FML, we add this"
    },
    {
      "name": "org.scala-lang:scala-compiler:2.10.2",
      "children" : ["sources"],
      "url" : "http://repo.maven.apache.org/maven2",
      "comment" : "Important for FML, we add this"
    },
    {
      "name": "net.sf.jopt-simple:jopt-simple:4.5",
      "children" : ["sources"],
      "url" : "http://repo.maven.apache.org/maven2"
    },
    {
      "name": "java3d:vecmath:1.3.1"
    },
    {
      "name": "net.sf.trove4j:trove4j:3.0.3"
    },
    {
      "name": "com.ibm.icu:icu4j-core-mojang:51.2"
    },
    {
      "name": "net.sf.jopt-simple:jopt-simple:4.5"
    },
    {
      "name": "lzma:lzma:0.0.1"
    },
    {
      "name": "com.paulscode:codecjorbis:20101023"
    },
    {
      "name": "com.paulscode:codecwav:20101023"
    },
    {
      "name": "com.paulscode:libraryjavasound:20101123"
    },
    {
      "name": "com.paulscode:librarylwjglopenal:20100824"
    },
    {
      "name": "com.paulscode:soundsystem:20120107"
    },
    {
      "name": "io.netty:netty-all:4.0.10.Final"
    },
    {
      "name": "com.google.guava:guava:15.0"
    },
    {
      "name": "org.apache.commons:commons-lang3:3.1"
    },
    {
      "name": "commons-io:commons-io:2.4"
    },
    {
      "name": "net.java.jinput:jinput:2.0.5"
    },
    {
      "name": "net.java.jutils:jutils:1.0.0"
    },
    {
      "name": "com.google.code.gson:gson:2.2.4"
    },
    {
      "name": "com.mojang:authlib:1.3"
    },
    {
      "name": "org.apache.logging.log4j:log4j-api:2.0-beta9"
    },
    {
      "name": "org.apache.logging.log4j:log4j-core:2.0-beta9"
    },
    {
      "name": "org.lwjgl.lwjgl:lwjgl:2.9.0",
      "rules": [
        {
          "action": "allow"
        },
        {
          "action": "disallow",
          "os": {
            "name": "osx"
          }
        }
      ]
    },
    {
      "name": "org.lwjgl.lwjgl:lwjgl_util:2.9.0",
      "rules": [
        {
          "action": "allow"
        },
        {
          "action": "disallow",
          "os": {
            "name": "osx"
          }
        }
      ]
    },
    {
      "name": "org.lwjgl.lwjgl:lwjgl-platform:2.9.0",
      "rules": [
        {
          "action": "allow"
        },
        {
          "action": "disallow",
          "os": {
            "name": "osx"
          }
        }
      ],
      "natives": {
        "linux": "natives-linux",
        "windows": "natives-windows"
      },
      "extract": {
        "exclude": [
          "META-INF/"
        ]
      }
    },
    {
      "name": "org.lwjgl.lwjgl:lwjgl:2.9.0",
      "rules": [
        {
          "action": "allow",
          "os": {
            "name": "osx"
          }
        }
      ]
    },
    {
      "name": "org.lwjgl.lwjgl:lwjgl_util:2.9.0",
      "rules": [
        {
          "action": "allow",
          "os": {
            "name": "osx"
          }
        }
      ]
    },
    {
      "name": "org.lwjgl.lwjgl:lwjgl-platform:2.9.0",
      "rules": [
        {
          "action": "allow",
          "os": {
            "name": "osx"
          }
        }
      ],
      "natives": {
        "osx": "natives-osx"
      },
      "extract": {
        "exclude": [
          "META-INF/"
        ]
      }
    },
    {
      "name": "net.java.jinput:jinput-platform:2.0.5",
      "natives": {
        "linux": "natives-linux",
        "windows": "natives-windows",
        "osx": "natives-osx"
      },
      "extract": {
        "exclude": [
          "META-INF/"
        ]
      }
    }
  ],
  "mainClass": "net.minecraft.launchwrapper.Launch",
  "minimumLauncherVersion": 9
}