diff --git a/.travis.yml b/.travis.yml
index 052b62b..5f441f5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,7 +9,10 @@ env:
   - TRAVIS_JDK=adopt-openj9@1.11.28-0
 
 before_install: curl -Ls https://git.io/jabba | bash && . ~/.jabba/jabba.sh
-install: jabba install "$TRAVIS_JDK" && jabba use $_ && java -Xmx32m -version
+
+install:
+  - jabba install "$TRAVIS_JDK" && jabba use $_ && java -Xmx32m -version
+  - mvn dependency:resolve
 
 stages:
   - validations
@@ -19,8 +22,9 @@ stages:
 jobs:
   include:
     - stage: validations
-      script: mvn -B clean install -DskipTests=true
       name: "Code validations (format, binary compatibilty, whitesource, etc.)"
+      script: mvn -B clean install -DskipTests=true -Pcheckstyle
+    - script: mvn -B clean install -DskipTests=true -Pchecker
 
 cache:
   directories:
diff --git a/build/checker/stubs/java.lang.Class.astub b/build/checker/stubs/java.lang.Class.astub
new file mode 100644
index 0000000..3db6bea
--- /dev/null
+++ b/build/checker/stubs/java.lang.Class.astub
@@ -0,0 +1,8 @@
+package java.lang;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class Class<T> {
+  // it *can* return null, but we only use it for loggers.
+  public @NonNull String getCanonicalName();
+}
diff --git a/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/CompressionAlgorithmFactory.java b/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/CompressionAlgorithmFactory.java
index 7079f8e..0456f01 100644
--- a/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/CompressionAlgorithmFactory.java
+++ b/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/CompressionAlgorithmFactory.java
@@ -16,6 +16,7 @@
 
 package de.bmarwell.zchunk.compression.api;
 
+import static java.util.stream.Collectors.toList;
 import static java.util.stream.Collectors.toMap;
 
 import de.bmarwell.zchunk.compression.algo.unknown.UnknownAlgorithm;
@@ -23,14 +24,18 @@
 import java.util.AbstractMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.stream.Stream;
+import org.checkerframework.checker.initialization.qual.UnderInitialization;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public final class CompressionAlgorithmFactory {
 
-  private static final Package THIS_PACKAGE = CompressionAlgorithmFactory.class.getPackage();
-  private static final String ROOT_PACKAGE = THIS_PACKAGE.getName().replaceAll("\\.api$", ".algo");
+  // do not change this as this would break plugins.
+  private static final String ROOT_PACKAGE = "io.github.zchunk.compression";
 
   private CompressionAlgorithmFactory() {
     // util class.
@@ -70,17 +75,18 @@ private static Map<Long, Class<CompressionAlgorithm>> getTypeMappings() {
 
   private static class ResourceHolder {
 
-    private static ResourceHolder INSTANCE = null;
+    private static @Nullable ResourceHolder INSTANCE = null;
 
     private final List<Class<CompressionAlgorithm>> implementations;
 
     private final Map<Long, Class<CompressionAlgorithm>> typeMapping;
 
     public ResourceHolder(final String rootPackage) {
-      this.implementations = ReflectionUtil.loadImplementations(rootPackage, CompressionAlgorithm.class);
+      this.implementations = loadImplementations(rootPackage, CompressionAlgorithm.class);
       this.typeMapping = loadTypeMapping(this.implementations);
     }
 
+    @EnsuresNonNull({"INSTANCE"})
     public static ResourceHolder newInstance(final String rootPackage) {
       if (INSTANCE == null) {
         INSTANCE = new ResourceHolder(rootPackage);
@@ -89,9 +95,32 @@ public static ResourceHolder newInstance(final String rootPackage) {
       return INSTANCE;
     }
 
-    private Map<Long, Class<CompressionAlgorithm>> loadTypeMapping(final List<Class<CompressionAlgorithm>> implementations) {
-      return implementations.stream()
-          .map(CompressionAlgorithmFactory::mapEntryOrNull)
+    /**
+     * Will try to load classes implementing clazz, from any package below rootpackage.
+     *
+     * @param rootPackage
+     *     the root package to search in.
+     * @param clazz
+     *     the class which should be implemented by the found classes.
+     * @param <T>
+     *     the class type.
+     * @return a list of classes implementing T / clazz.
+     */
+    public <T> List<Class<T>> loadImplementations(@UnderInitialization ResourceHolder this,
+        final String rootPackage,
+        final Class<T> clazz) {
+      final List<Class<T>> classes = ReflectionUtil.getClasses(rootPackage, clazz);
+
+      return classes.stream()
+          .filter(ReflectionUtil.classImplementsCompressionAlgorithm(clazz))
+          .collect(toList());
+    }
+
+    private Map<Long, Class<CompressionAlgorithm>> loadTypeMapping(@UnderInitialization ResourceHolder this,
+        final List<Class<CompressionAlgorithm>> implementations) {
+      final Stream<@Nullable Entry<Long, Class<CompressionAlgorithm>>> entryStream = implementations.stream()
+          .map(CompressionAlgorithmFactory::mapEntryOrNull);
+      return entryStream
           .filter(Objects::nonNull)
           .collect(toMap(Map.Entry::getKey, Map.Entry::getValue));
     }
diff --git a/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/internal/ReflectionUtil.java b/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/internal/ReflectionUtil.java
index d2518fd..0eeb5de 100644
--- a/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/internal/ReflectionUtil.java
+++ b/compression/compression-api/src/main/java/de/bmarwell/zchunk/compression/api/internal/ReflectionUtil.java
@@ -17,7 +17,6 @@
 package de.bmarwell.zchunk.compression.api.internal;
 
 import static java.util.Collections.emptyList;
-import static java.util.Collections.singletonList;
 import static java.util.stream.Collectors.toList;
 
 import java.io.File;
@@ -33,7 +32,6 @@
 import java.util.function.Predicate;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 public final class ReflectionUtil {
 
@@ -43,27 +41,7 @@ private ReflectionUtil() {
     // util
   }
 
-  /**
-   * Will try to load classes implementing clazz, from any package below rootpackage.
-   *
-   * @param rootPackage
-   *     the root package to search in.
-   * @param clazz
-   *     the class which should be implemented by the found classes.
-   * @param <T>
-   *     the class type.
-   * @return a list of classes implementing T / clazz.
-   */
-  public static <T> List<Class<T>> loadImplementations(final String rootPackage, final Class<T> clazz) {
-    final List<Class<T>> classes = getClasses(rootPackage, clazz);
-
-    return classes.stream()
-        .filter(classImplementsCompressionAlgorithm(clazz))
-        .collect(toList());
-  }
-
-
-  private static <T> List<Class<T>> getClasses(final String rootPackage, final Class<T> targetClazz) {
+  public static <T> List<Class<T>> getClasses(final String rootPackage, final Class<T> targetClazz) {
     try {
       final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
       final String path = rootPackage.replace('.', '/');
@@ -84,7 +62,6 @@ private static <T> List<Class<T>> getClasses(final String rootPackage, final Cla
     }
   }
 
-
   /**
    * Recursive method used to find all classes in a given directory and subdirs.
    *
@@ -118,27 +95,27 @@ private static <T> List<Class<T>> findClasses(final String packageName, final Cl
     }
 
     if (file.getName().endsWith(".class")) {
-      final @Nullable Class<T> aClass = loadClass(packageName, clazzType, file);
-      if (aClass != null) {
-        return singletonList(aClass);
-      }
+      return loadClass(packageName, clazzType, file)
+          .map(Collections::singletonList)
+          .orElseGet(Collections::emptyList);
     }
 
     return emptyList();
   }
 
-  @Nullable
-  private static <T> Class<T> loadClass(final String packageName, final Class<T> clazzType, final File file) {
+  private static <T> Optional<Class<T>> loadClass(final String packageName, final Class<T> clazzType, final File file) {
     try {
       final Class<?> aClass = Class.forName(packageName + '.' + file.getName().substring(0, file.getName().length() - 6));
       if (classImplementsCompressionAlgorithm(clazzType).test(aClass)) {
-        return (Class<T>) aClass;
+        @SuppressWarnings("unchecked")
+        final Class<T> castedClass = (Class<T>) aClass;
+        return Optional.ofNullable(castedClass);
       }
     } catch (final ClassNotFoundException e) {
       LOG.log(Level.WARNING, e, () -> String.format("Class file [%s] found, but unable to create instance.", file.getAbsolutePath()));
     }
 
-    return null;
+    return Optional.empty();
   }
 
   private static <T> List<T> getListFromArray(final T[] input) {
@@ -165,7 +142,7 @@ public static <T> Optional<T> newInstance(final Class<T> clazz) {
     }
   }
 
-  private static <T> Predicate<Class<?>> classImplementsCompressionAlgorithm(final Class<T> type) {
+  public static <T> Predicate<Class<?>> classImplementsCompressionAlgorithm(final Class<T> type) {
     return clazz -> getListFromArray(type.getInterfaces()).contains(type);
   }
 
diff --git a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkConstants.java b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkConstants.java
index 0489827..727643f 100644
--- a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkConstants.java
+++ b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkConstants.java
@@ -21,12 +21,15 @@
 import de.bmarwell.zchunk.compressedint.CompressedIntUtil;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-import java.security.Provider;
+import java.security.Provider.Service;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Objects;
 import java.util.Set;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public final class ZChunkConstants {
 
@@ -50,13 +53,13 @@ private static int getLargestHashSize() {
       final String digestClassName = MessageDigest.class.getSimpleName();
       final String aliasPrefix = "Alg.Alias." + digestClassName + ".";
 
-      return Arrays.stream(getProviders())
+      final Stream<@Nullable MessageDigest> messageDigestStream = Arrays.stream(getProviders())
           .flatMap(prov -> {
             final Set<String> algorithms = new HashSet<>(0);
 
             prov.getServices().stream()
                 .filter(s -> digestClassName.equalsIgnoreCase(s.getType()))
-                .map(Provider.Service::getAlgorithm)
+                .map(Service::getAlgorithm)
                 .collect(Collectors.toCollection(() -> algorithms));
 
             prov.keySet().stream()
@@ -67,16 +70,25 @@ private static int getLargestHashSize() {
 
             return algorithms.stream();
           })
-          .map(algo -> {
-            try {
-              return MessageDigest.getInstance(algo);
-            } catch (NoSuchAlgorithmException e) {
-              return null;
-            }
-          })
-          .filter(Objects::nonNull)
+          .map(ZChunkConstants::instanceOrNull);
+
+      return toNonNullStream(messageDigestStream)
           .mapToInt(MessageDigest::getDigestLength)
           .max().orElse(512 / 8);
     }
+
+  }
+
+  @SuppressWarnings("nullness")
+  private static Stream<@NonNull MessageDigest> toNonNullStream(final Stream<@Nullable MessageDigest> messageDigestStream) {
+    return messageDigestStream.filter(Objects::nonNull);
+  }
+
+  private static @Nullable MessageDigest instanceOrNull(final String algo) {
+    try {
+      return MessageDigest.getInstance(algo);
+    } catch (final NoSuchAlgorithmException e) {
+      return null;
+    }
   }
 }
diff --git a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkHeaderFactory.java b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkHeaderFactory.java
index a9451de..46f86ec 100644
--- a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkHeaderFactory.java
+++ b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/ZChunkHeaderFactory.java
@@ -90,7 +90,7 @@ public static ZChunkHeader fromStream(final InputStream byteStream) {
 
       final ZChunkHeaderPreface headerPreface = readHeaderPreface(completeHeader, lead);
 
-      final ZChunkHeaderIndex index = null;
+      final ZChunkHeaderIndex index = readHeaderIndex(completeHeader, lead, headerPreface);
       final ZChunkHeaderSignatures signature = ImmutableZChunkHeaderSignatures.builder()
           .signatureCount(CompressedIntFactory.valueOf(0L))
           .build();
diff --git a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkIndexParser.java b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkIndexParser.java
index ccc0979..4e11d7d 100644
--- a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkIndexParser.java
+++ b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkIndexParser.java
@@ -32,6 +32,9 @@
 import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.List;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public final class ZChunkIndexParser {
 
@@ -46,8 +49,8 @@ public final class ZChunkIndexParser {
   private long dictLengthOffset = -1L;
   private long dictUncompressedLengthOffset = -1L;
   private long chunkStreamOffset = -1L;
-  private CompressedInt chunkCount;
-  private IndexChecksumType chunkChecksumType;
+  private @Nullable CompressedInt chunkCount;
+  private @Nullable IndexChecksumType chunkChecksumType;
 
   private ZChunkIndexParser(final byte[] completeHeader, final ZChunkHeaderLead lead, final ZChunkHeaderPreface preface) {
     this.completeHeader = completeHeader;
@@ -72,6 +75,7 @@ public CompressedInt readIndexSize() {
     }
   }
 
+  @EnsuresNonNull("chunkChecksumType")
   public CompressedInt readIndexCksumType() {
     if (this.cksumTypeOffset == -1L) {
       readIndexSize();
@@ -89,6 +93,7 @@ public CompressedInt readIndexCksumType() {
     }
   }
 
+  @EnsuresNonNull("chunkCount")
   public CompressedInt readChunkCount() {
     if (this.chunkCountOffset == -1) {
       readIndexCksumType();
@@ -122,15 +127,18 @@ public byte[] readDictStream() {
   }
 
   public byte[] readDictChecksum() {
-    if (this.dictChecksumOffest == -1L) {
+    if (this.dictChecksumOffest == -1L || null == this.chunkChecksumType) {
       readDictStream();
     }
 
     try (final ByteArrayInputStream bis = new ByteArrayInputStream(this.completeHeader)) {
       bis.skip(this.dictChecksumOffest);
 
-      // TODO. Which checksum does the dict use? chunk or header checksum?
-      final int dictChecksumLength = this.chunkChecksumType.actualChecksumLength();
+      // safe to assume, as it is never set back to null.
+      @SuppressWarnings("nullness")
+      @NonNull
+      final IndexChecksumType chunkChecksumType = this.chunkChecksumType;
+      final int dictChecksumLength = chunkChecksumType.actualChecksumLength();
       final byte[] dictChecksum = new byte[dictChecksumLength];
       bis.read(dictChecksum);
 
@@ -177,11 +185,20 @@ public CompressedInt readUncompressedDictLength() {
   }
 
   public List<? extends ZChunkHeaderChunkInfo> readChunkInfos() {
-    if (this.chunkStreamOffset == -1L) {
+    if (this.chunkStreamOffset == -1L || null == this.chunkChecksumType || null == this.chunkCount) {
       readUncompressedDictLength();
     }
 
-    if (this.chunkCount.getValue().equals(BigInteger.ZERO)) {
+    // safe to assume, as it is never set back to null.
+    @SuppressWarnings("nullness")
+    @NonNull
+    final IndexChecksumType chunkChecksumType = this.chunkChecksumType;
+    // safe to assume, as it is never set back to null.
+    @SuppressWarnings("nullness")
+    @NonNull
+    final CompressedInt chunkCount = this.chunkCount;
+
+    if (chunkCount.getValue().equals(BigInteger.ZERO)) {
       return emptyList();
     }
 
@@ -189,7 +206,7 @@ public List<? extends ZChunkHeaderChunkInfo> readChunkInfos() {
 
     long currentOffset = 0;
     // first chunk is the dict chunk.
-    for (long chunkNumber = 0; chunkNumber < this.chunkCount.getLongValue() - 1L; chunkNumber++) {
+    for (long chunkNumber = 0; chunkNumber < chunkCount.getLongValue() - 1L; chunkNumber++) {
       try (final ByteArrayInputStream bis = new ByteArrayInputStream(this.completeHeader)) {
         bis.skip(this.chunkStreamOffset + currentOffset);
         if (this.preface.getPrefaceFlags().contains(PrefaceFlag.HAS_DATA_STREAMS)) {
@@ -197,7 +214,7 @@ public List<? extends ZChunkHeaderChunkInfo> readChunkInfos() {
           throw new UnsupportedOperationException("data streams not implemented.");
         }
 
-        final byte[] chunkChecksum = new byte[this.chunkChecksumType.actualChecksumLength()];
+        final byte[] chunkChecksum = new byte[chunkChecksumType.actualChecksumLength()];
         bis.read(chunkChecksum);
 
         final CompressedInt compressedChunkLength = CompressedIntFactory.readCompressedInt(bis);
@@ -210,7 +227,7 @@ public List<? extends ZChunkHeaderChunkInfo> readChunkInfos() {
             .chunkUncompressedLength(uncompressedChunkLength)
             .build());
 
-        currentOffset += this.chunkChecksumType.actualChecksumLength()
+        currentOffset += chunkChecksumType.actualChecksumLength()
             + compressedChunkLength.getCompressedBytes().length
             + uncompressedChunkLength.getCompressedBytes().length;
       } catch (final IOException ioEx) {
diff --git a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkLeadParser.java b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkLeadParser.java
index db7bbeb..dc942d6 100644
--- a/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkLeadParser.java
+++ b/fileformat/src/main/java/de/bmarwell/zchunk/fileformat/parser/ZChunkLeadParser.java
@@ -27,11 +27,14 @@
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class ZChunkLeadParser {
 
   private final byte[] leadBytes = new byte[MAX_LEAD_SIZE];
-  private HeaderChecksumType checksumType;
+  private @Nullable HeaderChecksumType checksumType;
   private long headerSizeOffset;
   private long headerChecksumOffset;
 
@@ -42,8 +45,11 @@ public class ZChunkLeadParser {
    *     the bytes belonging to the lead.
    */
   private ZChunkLeadParser(final byte[] leadBytes) {
-    if (leadBytes.length < MAX_LEAD_SIZE) {
-      throw new IllegalArgumentException("");
+    final int length = leadBytes.length;
+
+    if (length < MAX_LEAD_SIZE) {
+      final String message = String.format("lead bytes are too short with [%d] bytes. Need at least [%d] bytes.", length, MAX_LEAD_SIZE);
+      throw new IllegalArgumentException(message);
     }
 
     System.arraycopy(leadBytes, 0, this.leadBytes, 0, MAX_LEAD_SIZE);
@@ -96,6 +102,7 @@ public byte[] readLeadId() {
     }
   }
 
+  @EnsuresNonNull("checksumType")
   public CompressedInt readLeadCksumType() {
     try (final ByteArrayInputStream bis = new ByteArrayInputStream(this.leadBytes)) {
       final long skip = bis.skip(FILE_MAGIC.length);
@@ -114,7 +121,7 @@ public CompressedInt readLeadCksumType() {
   }
 
   public CompressedInt readHeaderSize() {
-    if (this.headerSizeOffset == -1L) {
+    if (this.headerSizeOffset == -1L || null == this.checksumType) {
       readLeadCksumType();
     }
 
@@ -130,11 +137,15 @@ public CompressedInt readHeaderSize() {
   }
 
   public byte[] readHeaderChecksum() {
-    if (this.headerChecksumOffset == -1L) {
+    if (this.headerChecksumOffset == -1L || null == this.checksumType) {
       readHeaderSize();
     }
 
-    final int cksumLength = this.checksumType.getDigestLength();
+    // as checksumType is never set back to null, this is safe to assume.
+    @SuppressWarnings("nullness")
+    @NonNull
+    final HeaderChecksumType checksumType = this.checksumType;
+    final int cksumLength = checksumType.getDigestLength();
 
     try (final ByteArrayInputStream bis = new ByteArrayInputStream(this.leadBytes)) {
       bis.skip(this.headerChecksumOffset);
diff --git a/pom.xml b/pom.xml
index 0ab4277..e0c6f14 100644
--- a/pom.xml
+++ b/pom.xml
@@ -38,9 +38,12 @@
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
     <!-- dependencies -->
+    <dependency.checker.version>2.8.1</dependency.checker.version>
     <dependency.immutables.version>2.7.5</dependency.immutables.version>
     <!-- test dependencies -->
     <dependency.junit-jupiter.version>5.4.0</dependency.junit-jupiter.version>
+
+    <checker.stubs.dir>${maven.multiModuleProjectDirectory}/build/checker/stubs</checker.stubs.dir>
   </properties>
 
   <dependencyManagement>
@@ -113,6 +116,12 @@
           </configuration>
         </plugin>
 
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-enforcer-plugin</artifactId>
+          <version>3.0.0-M2</version>
+        </plugin>
+
         <!-- maven checkstyle -->
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
@@ -144,19 +153,146 @@
     <plugins>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-checkstyle-plugin</artifactId>
-        <version>3.0.0</version>
-        <executions>
-          <execution>
-            <id>checkstyle-check</id>
-            <phase>validate</phase>
-            <goals>
-              <goal>check</goal>
-            </goals>
-          </execution>
-        </executions>
+        <artifactId>maven-enforcer-plugin</artifactId>
+        <configuration>
+          <rules>
+            <requireMavenVersion>
+              <version>[3.3.1,)</version>
+            </requireMavenVersion>
+
+            <requireJavaVersion>
+              <version>[1.8,)</version>
+            </requireJavaVersion>
+
+            <bannedDependencies>
+              <excludes>
+                <exclude>org.apache.maven</exclude>
+                <exclude>com.google</exclude>
+                <exclude>org.slf4j</exclude>
+              </excludes>
+            </bannedDependencies>
+          </rules>
+        </configuration>
       </plugin>
     </plugins>
+
   </build>
 
+  <profiles>
+    <profile>
+      <id>checkstyle</id>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-checkstyle-plugin</artifactId>
+            <version>3.0.0</version>
+            <executions>
+              <execution>
+                <id>checkstyle-check</id>
+                <phase>validate</phase>
+                <goals>
+                  <goal>check</goal>
+                </goals>
+              </execution>
+            </executions>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+
+    <profile>
+      <id>checker</id>
+      <properties>
+        <checker.version>2.5.6</checker.version>
+      </properties>
+      <dependencies>
+        <dependency>
+          <groupId>org.checkerframework</groupId>
+          <artifactId>checker-qual</artifactId>
+          <version>${dependency.checker.version}</version>
+          <optional>true</optional>
+        </dependency>
+        <dependency>
+          <groupId>org.checkerframework</groupId>
+          <artifactId>checker</artifactId>
+          <version>${dependency.checker.version}</version>
+          <optional>true</optional>
+        </dependency>
+        <dependency>
+          <groupId>org.checkerframework</groupId>
+          <artifactId>jdk8</artifactId>
+          <version>${dependency.checker.version}</version>
+          <optional>true</optional>
+        </dependency>
+        <dependency>
+          <!-- not all modules have dependency on immutables (e.g. jdbc-plugin) but need it on
+            the classpath for the explicit annotation processing setup below -->
+          <groupId>org.immutables</groupId>
+          <artifactId>value</artifactId>
+          <version>${dependency.immutables.version}</version>
+        </dependency>
+      </dependencies>
+
+      <build>
+        <plugins>
+          <plugin>
+            <artifactId>maven-enforcer-plugin</artifactId>
+            <executions>
+              <execution>
+                <goals>
+                  <goal>enforce</goal>
+                </goals>
+                <configuration>
+                  <rules>
+                  </rules>
+                </configuration>
+              </execution>
+            </executions>
+          </plugin>
+          <plugin>
+            <artifactId>maven-dependency-plugin</artifactId>
+            <executions>
+              <execution>
+                <goals>
+                  <goal>properties</goal>
+                </goals>
+              </execution>
+            </executions>
+          </plugin>
+          <plugin>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <configuration>
+              <source>1.8</source>
+              <target>1.8</target>
+              <maxmem>512m</maxmem>
+              <annotationProcessors>
+                <annotationProcessor>
+                  org.immutables.value.internal.$processor$.$Processor
+                </annotationProcessor>
+                <annotationProcessor>
+                  org.checkerframework.checker.nullness.NullnessChecker
+                </annotationProcessor>
+                <annotationProcessor>
+                  org.checkerframework.checker.tainting.TaintingChecker
+                </annotationProcessor>
+              </annotationProcessors>
+              <compilerArgs>
+                <arg>-Xbootclasspath/p:${org.checkerframework:jdk8:jar}</arg>
+                <!-- checker.stubs.dir needs to be absolute path since relative path will be
+                  interpreted from each module directory -->
+                <arg>-Astubs=${checker.stubs.dir}</arg>
+                <arg>
+                  -AskipDefs=^de\.bmarwell\.zchunk\..*\.ReflectionUtil$|io\.github\.zchunk\..*\.ReflectionUtil$
+                  |^de\.bmarwell\.zchunk\..*\.ChecksumUtil$|^io\.github\.zchunk\..*\.ChecksumUtil$
+                  |^.*Test$
+                </arg>
+              </compilerArgs>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+  </profiles>
+
 </project>