diff --git a/dev/checkstyle/checkstyle.xml b/dev/checkstyle/checkstyle.xml
index 9f19037..2317e0d 100644
--- a/dev/checkstyle/checkstyle.xml
+++ b/dev/checkstyle/checkstyle.xml
@@ -33,7 +33,6 @@
     <!-- File must start with the C Thing copyright header -->
     <module name="RegexpHeader">
         <property name="headerFile" value="${config_loc}/header.txt"/>
-        <property name="multiLines" value="3"/>
     </module>
 
     <!-- Flag IDE generated comments -->
diff --git a/dev/checkstyle/header.txt b/dev/checkstyle/header.txt
index c448c3c..11bd74f 100644
--- a/dev/checkstyle/header.txt
+++ b/dev/checkstyle/header.txt
@@ -1,14 +1,3 @@
 ^/\*$
 ^ \* Copyright [\d]{4}((,[\s]*[\d]{4})*|(-[\d]{4})?) C Thing Software$
-^ \*$
-^ \* Licensed under the Apache License, Version 2\.0 \(the "License"\);$
-^ \* you may not use this file except in compliance with the License\.$
-^ \* You may obtain a copy of the License at$
-^ \*$
-^ \*     http://www\.apache\.org/licenses/LICENSE-2\.0$
-^ \*$
-^ \* Unless required by applicable law or agreed to in writing, software$
-^ \* distributed under the License is distributed on an "AS IS" BASIS,$
-^ \* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied\.$
-^ \* See the License for the specific language governing permissions and$
-^ \* limitations under the License\.$
+^ \* SPDX-License-Identifier: Apache-2.0$
diff --git a/src/main/java/org/cthing/escapers/AbstractEscaper.java b/src/main/java/org/cthing/escapers/AbstractEscaper.java
index 2ed235c..bed02c1 100644
--- a/src/main/java/org/cthing/escapers/AbstractEscaper.java
+++ b/src/main/java/org/cthing/escapers/AbstractEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/CodePointProvider.java b/src/main/java/org/cthing/escapers/CodePointProvider.java
index a4a7cd2..54fef16 100644
--- a/src/main/java/org/cthing/escapers/CodePointProvider.java
+++ b/src/main/java/org/cthing/escapers/CodePointProvider.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/CsvEscaper.java b/src/main/java/org/cthing/escapers/CsvEscaper.java
index 217897e..c1615f5 100644
--- a/src/main/java/org/cthing/escapers/CsvEscaper.java
+++ b/src/main/java/org/cthing/escapers/CsvEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/HexUtils.java b/src/main/java/org/cthing/escapers/HexUtils.java
index fb26cdc..7cf2515 100644
--- a/src/main/java/org/cthing/escapers/HexUtils.java
+++ b/src/main/java/org/cthing/escapers/HexUtils.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -59,8 +48,7 @@ static void writeHex2(final int value, final Writer writer) throws IOException {
     static void writeHex4(final int value, final Writer writer) throws IOException {
         writer.write(HEX_DIGITS[value >> 12 & 0xF]);
         writer.write(HEX_DIGITS[value >> 8 & 0xF]);
-        writer.write(HEX_DIGITS[value >> 4 & 0xF]);
-        writer.write(HEX_DIGITS[value & 0xF]);
+        writeHex2(value, writer);
     }
 
     /**
@@ -76,10 +64,7 @@ static void writeHex8(final int value, final Writer writer) throws IOException {
         writer.write(HEX_DIGITS[value >> 24 & 0xF]);
         writer.write(HEX_DIGITS[value >> 20 & 0xF]);
         writer.write(HEX_DIGITS[value >> 16 & 0xF]);
-        writer.write(HEX_DIGITS[value >> 12 & 0xF]);
-        writer.write(HEX_DIGITS[value >> 8 & 0xF]);
-        writer.write(HEX_DIGITS[value >> 4 & 0xF]);
-        writer.write(HEX_DIGITS[value & 0xF]);
+        writeHex4(value, writer);
     }
 
     /**
diff --git a/src/main/java/org/cthing/escapers/HtmlEntities.java b/src/main/java/org/cthing/escapers/HtmlEntities.java
index a743669..eeae799 100644
--- a/src/main/java/org/cthing/escapers/HtmlEntities.java
+++ b/src/main/java/org/cthing/escapers/HtmlEntities.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/HtmlEscaper.java b/src/main/java/org/cthing/escapers/HtmlEscaper.java
index 21afa08..7b315a5 100644
--- a/src/main/java/org/cthing/escapers/HtmlEscaper.java
+++ b/src/main/java/org/cthing/escapers/HtmlEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -411,7 +400,6 @@ private static String escape(final CodePointProvider codePointProvider, final in
         }
     }
 
-    @SuppressWarnings("ForLoopReplaceableByForEach")
     private static void escape(final CodePointProvider codePointProvider, final int offset, final int length,
                                final Writer writer, final Set<Option> options) throws IOException {
         if (writer == null) {
diff --git a/src/main/java/org/cthing/escapers/JavaEscaper.java b/src/main/java/org/cthing/escapers/JavaEscaper.java
index f65f85c..05e9880 100644
--- a/src/main/java/org/cthing/escapers/JavaEscaper.java
+++ b/src/main/java/org/cthing/escapers/JavaEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/JavaScriptEscaper.java b/src/main/java/org/cthing/escapers/JavaScriptEscaper.java
index f68cdbb..908708f 100644
--- a/src/main/java/org/cthing/escapers/JavaScriptEscaper.java
+++ b/src/main/java/org/cthing/escapers/JavaScriptEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/JsonEscaper.java b/src/main/java/org/cthing/escapers/JsonEscaper.java
index ceaf133..a4d16b1 100644
--- a/src/main/java/org/cthing/escapers/JsonEscaper.java
+++ b/src/main/java/org/cthing/escapers/JsonEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/XmlEscaper.java b/src/main/java/org/cthing/escapers/XmlEscaper.java
index 1d95824..6f955c4 100644
--- a/src/main/java/org/cthing/escapers/XmlEscaper.java
+++ b/src/main/java/org/cthing/escapers/XmlEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/YamlEscaper.java b/src/main/java/org/cthing/escapers/YamlEscaper.java
index a83c4bf..6cc1a19 100644
--- a/src/main/java/org/cthing/escapers/YamlEscaper.java
+++ b/src/main/java/org/cthing/escapers/YamlEscaper.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/main/java/org/cthing/escapers/package-info.java b/src/main/java/org/cthing/escapers/package-info.java
index afd03d0..8ff725b 100644
--- a/src/main/java/org/cthing/escapers/package-info.java
+++ b/src/main/java/org/cthing/escapers/package-info.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 /**
diff --git a/src/test/java/org/cthing/escapers/AbstractVarargsAggregator.java b/src/test/java/org/cthing/escapers/AbstractVarargsAggregator.java
index 2e636ff..0e8c160 100644
--- a/src/test/java/org/cthing/escapers/AbstractVarargsAggregator.java
+++ b/src/test/java/org/cthing/escapers/AbstractVarargsAggregator.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -36,7 +25,6 @@ protected AbstractVarargsAggregator(final Class<T> optionsType, final int startI
     }
 
     @Override
-    @SuppressWarnings("unchecked")
     public Set<T> aggregateArguments(final ArgumentsAccessor arguments, final ParameterContext context) {
         return IntStream.range(this.startIndex, arguments.size())
                         .mapToObj(i -> arguments.get(i, this.optionsType))
diff --git a/src/test/java/org/cthing/escapers/CsvEscaperTest.java b/src/test/java/org/cthing/escapers/CsvEscaperTest.java
index aa976fe..67c63f6 100644
--- a/src/test/java/org/cthing/escapers/CsvEscaperTest.java
+++ b/src/test/java/org/cthing/escapers/CsvEscaperTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -31,7 +20,6 @@
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 
-@SuppressWarnings("DataFlowIssue")
 public class CsvEscaperTest {
 
     public static Stream<Arguments> escapeProvider() {
diff --git a/src/test/java/org/cthing/escapers/HexUtilsTest.java b/src/test/java/org/cthing/escapers/HexUtilsTest.java
index d73804d..5ccdf1e 100644
--- a/src/test/java/org/cthing/escapers/HexUtilsTest.java
+++ b/src/test/java/org/cthing/escapers/HexUtilsTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
diff --git a/src/test/java/org/cthing/escapers/HtmlEscaperTest.java b/src/test/java/org/cthing/escapers/HtmlEscaperTest.java
index 3e4c58b..3eca1e9 100644
--- a/src/test/java/org/cthing/escapers/HtmlEscaperTest.java
+++ b/src/test/java/org/cthing/escapers/HtmlEscaperTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -39,7 +28,7 @@
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 
-@SuppressWarnings({ "DataFlowIssue", "UnnecessaryUnicodeEscape" })
+@SuppressWarnings("UnnecessaryUnicodeEscape")
 public class HtmlEscaperTest {
 
     public static Stream<Arguments> escapeProvider() {
diff --git a/src/test/java/org/cthing/escapers/JavaEscaperTest.java b/src/test/java/org/cthing/escapers/JavaEscaperTest.java
index d79af8b..5f47674 100644
--- a/src/test/java/org/cthing/escapers/JavaEscaperTest.java
+++ b/src/test/java/org/cthing/escapers/JavaEscaperTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -39,7 +28,7 @@
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 
-@SuppressWarnings({ "UnnecessaryUnicodeEscape", "DataFlowIssue" })
+@SuppressWarnings("UnnecessaryUnicodeEscape")
 public class JavaEscaperTest {
 
     public static Stream<Arguments> escapeProvider() {
diff --git a/src/test/java/org/cthing/escapers/JavaScriptEscaperTest.java b/src/test/java/org/cthing/escapers/JavaScriptEscaperTest.java
index af4faa5..b0b5b67 100644
--- a/src/test/java/org/cthing/escapers/JavaScriptEscaperTest.java
+++ b/src/test/java/org/cthing/escapers/JavaScriptEscaperTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -39,7 +28,7 @@
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 
-@SuppressWarnings({ "UnnecessaryUnicodeEscape", "DataFlowIssue" })
+@SuppressWarnings("UnnecessaryUnicodeEscape")
 public class JavaScriptEscaperTest {
 
     public static Stream<Arguments> escapeProvider() {
diff --git a/src/test/java/org/cthing/escapers/JsonEscaperTest.java b/src/test/java/org/cthing/escapers/JsonEscaperTest.java
index 62e69cc..0d69d56 100644
--- a/src/test/java/org/cthing/escapers/JsonEscaperTest.java
+++ b/src/test/java/org/cthing/escapers/JsonEscaperTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -39,7 +28,7 @@
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 
-@SuppressWarnings({ "UnnecessaryUnicodeEscape", "DataFlowIssue" })
+@SuppressWarnings("UnnecessaryUnicodeEscape")
 public class JsonEscaperTest {
 
     public static Stream<Arguments> escapeProvider() {
diff --git a/src/test/java/org/cthing/escapers/XmlEscaperTest.java b/src/test/java/org/cthing/escapers/XmlEscaperTest.java
index 450afa5..9db1822 100644
--- a/src/test/java/org/cthing/escapers/XmlEscaperTest.java
+++ b/src/test/java/org/cthing/escapers/XmlEscaperTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -39,7 +28,7 @@
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 
-@SuppressWarnings({ "UnnecessaryUnicodeEscape", "DataFlowIssue" })
+@SuppressWarnings("UnnecessaryUnicodeEscape")
 public class XmlEscaperTest {
 
     public static Stream<Arguments> escapeProvider() {
diff --git a/src/test/java/org/cthing/escapers/YamlEscaperTest.java b/src/test/java/org/cthing/escapers/YamlEscaperTest.java
index f7d0b11..afc0265 100644
--- a/src/test/java/org/cthing/escapers/YamlEscaperTest.java
+++ b/src/test/java/org/cthing/escapers/YamlEscaperTest.java
@@ -1,17 +1,6 @@
 /*
  * Copyright 2024 C Thing Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package org.cthing.escapers;
@@ -40,7 +29,7 @@
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 
-@SuppressWarnings({ "UnnecessaryUnicodeEscape", "DataFlowIssue" })
+@SuppressWarnings("UnnecessaryUnicodeEscape")
 public class YamlEscaperTest {
 
     public static Stream<Arguments> quotesProvider() {