diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/builder/CertificationSignatureBuilder.java b/pgpainless-core/src/main/java/org/pgpainless/signature/builder/CertificationSignatureBuilder.java
index 03801204..792658ee 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/builder/CertificationSignatureBuilder.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/builder/CertificationSignatureBuilder.java
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
 package org.pgpainless.signature.builder;
 
 import org.bouncycastle.openpgp.PGPException;
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/builder/RevocationSignatureBuilder.java b/pgpainless-core/src/main/java/org/pgpainless/signature/builder/RevocationSignatureBuilder.java
index bd7bef31..db263f07 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/builder/RevocationSignatureBuilder.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/builder/RevocationSignatureBuilder.java
@@ -37,5 +37,7 @@ public class RevocationSignatureBuilder extends AbstractSignatureBuilder<Revocat
         return unhashedSubpackets;
     }
 
-    public PGPSignature build()
+    public PGPSignature build() {
+        return null;
+    }
 }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/builder/package-info.java b/pgpainless-core/src/main/java/org/pgpainless/signature/builder/package-info.java
new file mode 100644
index 00000000..c82eb0ec
--- /dev/null
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/builder/package-info.java
@@ -0,0 +1,8 @@
+// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+/**
+ * Classes related to OpenPGP signatures.
+ */
+package org.pgpainless.signature.builder;
diff --git a/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketGeneratorWrapper.java b/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketGeneratorWrapper.java
index 59ce6a47..5a4e72d3 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketGeneratorWrapper.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/signature/subpackets/SignatureSubpacketGeneratorWrapper.java
@@ -549,12 +549,10 @@ public class SignatureSubpacketGeneratorWrapper
         byte[] sig = signature.getEncoded();
         byte[] data;
 
-        if (sig.length - 1 > 256)
-        {
+        if (sig.length - 1 > 256) {
             data = new byte[sig.length - 3];
         }
-        else
-        {
+        else {
             data = new byte[sig.length - 2];
         }