3 files changed, 9 insertions, 10 deletions

diff --git a/app/src/main/java/com/wireguard/config/Config.java b/app/src/main/java/com/wireguard/config/Config.java
index 7b9bcab3..d2c1395f 100644
--- a/app/src/main/java/com/wireguard/config/Config.java
+++ b/app/src/main/java/com/wireguard/config/Config.java
@@ -30,9 +30,7 @@ public final class Config {
     private final List<Peer> peers;
 
     private Config(final Builder builder) {
-        if (builder.interfaze == null)
-            throw new IllegalArgumentException("An [Interface] section is required");
-        interfaze = builder.interfaze;
+        interfaze = Objects.requireNonNull(builder.interfaze, "An [Interface] section is required");
         // Defensively copy to ensure immutability even if the Builder is reused.
         peers = Collections.unmodifiableList(new ArrayList<>(builder.peers));
     }
@@ -189,6 +187,8 @@ public final class Config {
         }
 
         public Config build() {
+            if (interfaze == null)
+                throw new IllegalArgumentException("An [Interface] section is required");
             return new Config(this);
         }
 
diff --git a/app/src/main/java/com/wireguard/config/Interface.java b/app/src/main/java/com/wireguard/config/Interface.java
index f97c4731..da30fbcc 100644
--- a/app/src/main/java/com/wireguard/config/Interface.java
+++ b/app/src/main/java/com/wireguard/config/Interface.java
@@ -44,14 +44,11 @@ public final class Interface {
     private final Optional<Integer> mtu;
 
     private Interface(final Builder builder) {
-        if (builder.keyPair == null)
-            throw new IllegalArgumentException("Interfaces must have a private key");
-
         // Defensively copy to ensure immutability even if the Builder is reused.
         addresses = Collections.unmodifiableSet(new LinkedHashSet<>(builder.addresses));
         dnsServers = Collections.unmodifiableSet(new LinkedHashSet<>(builder.dnsServers));
         excludedApplications = Collections.unmodifiableSet(new LinkedHashSet<>(builder.excludedApplications));
-        keyPair = builder.keyPair;
+        keyPair = Objects.requireNonNull(builder.keyPair, "Interfaces must have a private key");
         listenPort = builder.listenPort;
         mtu = builder.mtu;
     }
@@ -264,6 +261,8 @@ public final class Interface {
         }
 
         public Interface build() {
+            if (keyPair == null)
+                throw new IllegalArgumentException("Interfaces must have a private key");
             return new Interface(this);
         }
 
diff --git a/app/src/main/java/com/wireguard/config/Peer.java b/app/src/main/java/com/wireguard/config/Peer.java
index 1eb30197..1250fcb3 100644
--- a/app/src/main/java/com/wireguard/config/Peer.java
+++ b/app/src/main/java/com/wireguard/config/Peer.java
@@ -35,14 +35,12 @@ public final class Peer {
     private final Key publicKey;
 
     private Peer(final Builder builder) {
-        if (builder.publicKey == null)
-            throw new IllegalArgumentException("Peers must have a public key");
         // Defensively copy to ensure immutability even if the Builder is reused.
         allowedIps = Collections.unmodifiableSet(new LinkedHashSet<>(builder.allowedIps));
         endpoint = builder.endpoint;
         persistentKeepalive = builder.persistentKeepalive;
         preSharedKey = builder.preSharedKey;
-        publicKey = builder.publicKey;
+        publicKey = Objects.requireNonNull(builder.publicKey, "Peers must have a public key");
     }
 
     /**
@@ -226,6 +224,8 @@ public final class Peer {
         }
 
         public Peer build() {
+            if (publicKey == null)
+                throw new IllegalArgumentException("Peers must have a public key");
             return new Peer(this);
         }