diff --git a/examples/isthmus-api/src/main/java/io/substrait/examples/SchemaHelper.java b/examples/isthmus-api/src/main/java/io/substrait/examples/SchemaHelper.java
index d3fe2cae7..e1c7732c8 100644
--- a/examples/isthmus-api/src/main/java/io/substrait/examples/SchemaHelper.java
+++ b/examples/isthmus-api/src/main/java/io/substrait/examples/SchemaHelper.java
@@ -19,7 +19,7 @@ private SchemaHelper() {}
    *
    * @param createStatements a SQL string containing only CREATE statements
    * @return a {@link CalciteCatalogReader} generated from the CREATE statements
-   * @throws SqlParseException
+   * @throws SqlParseException if the sql can not be parsed
    */
   public static CalciteSchema processCreateStatementsToSchema(final List<String> createStatements)
       throws SqlParseException {
diff --git a/examples/substrait-spark/src/main/java/io/substrait/examples/util/ExpressionStringify.java b/examples/substrait-spark/src/main/java/io/substrait/examples/util/ExpressionStringify.java
index 2503ca091..413f9b9b9 100644
--- a/examples/substrait-spark/src/main/java/io/substrait/examples/util/ExpressionStringify.java
+++ b/examples/substrait-spark/src/main/java/io/substrait/examples/util/ExpressionStringify.java
@@ -48,10 +48,15 @@
 import io.substrait.util.EmptyVisitationContext;
 import java.util.List;
 
-/** ExpressionStringify gives a simple debug text output for Expressions */
+/** ExpressionStringify gives a simple debug text output for Expressions. */
 public class ExpressionStringify extends ParentStringify
     implements ExpressionVisitor<String, EmptyVisitationContext, RuntimeException> {
 
+  /**
+   * Constructor.
+   *
+   * @param indent indent size
+   */
   public ExpressionStringify(int indent) {
     super(indent);
   }
diff --git a/examples/substrait-spark/src/main/java/io/substrait/examples/util/FunctionArgStringify.java b/examples/substrait-spark/src/main/java/io/substrait/examples/util/FunctionArgStringify.java
index 372b7e79f..dcd2d8f4b 100644
--- a/examples/substrait-spark/src/main/java/io/substrait/examples/util/FunctionArgStringify.java
+++ b/examples/substrait-spark/src/main/java/io/substrait/examples/util/FunctionArgStringify.java
@@ -11,6 +11,11 @@
 public class FunctionArgStringify extends ParentStringify
     implements FuncArgVisitor<String, EmptyVisitationContext, RuntimeException> {
 
+  /**
+   * Constructor
+   *
+   * @param indent number of indents to use
+   */
   public FunctionArgStringify(int indent) {
     super(indent);
   }
diff --git a/examples/substrait-spark/src/main/java/io/substrait/examples/util/ParentStringify.java b/examples/substrait-spark/src/main/java/io/substrait/examples/util/ParentStringify.java
index 62535bedc..878d96a5f 100644
--- a/examples/substrait-spark/src/main/java/io/substrait/examples/util/ParentStringify.java
+++ b/examples/substrait-spark/src/main/java/io/substrait/examples/util/ParentStringify.java
@@ -6,8 +6,13 @@
  */
 public class ParentStringify {
 
+  /** Indent character. */
   protected String indentChar = " ";
+
+  /** Indents of idnentsize to use. */
   protected int indent;
+
+  /** Size of each indent. */
   protected int indentSize = 3;
 
   /**
@@ -50,6 +55,12 @@ StringBuilder getContinuationIndentString() {
     return sb;
   }
 
+  /**
+   * Get the outdent to use, decreats indent counter.
+   *
+   * @param sb Stribug Builder with outdent
+   * @return outdent string
+   */
   protected String getOutdent(StringBuilder sb) {
     indent--;
     return (sb).toString();
diff --git a/examples/substrait-spark/src/main/java/io/substrait/examples/util/SubstraitStringify.java b/examples/substrait-spark/src/main/java/io/substrait/examples/util/SubstraitStringify.java
index a94d47fd4..cdab68cda 100644
--- a/examples/substrait-spark/src/main/java/io/substrait/examples/util/SubstraitStringify.java
+++ b/examples/substrait-spark/src/main/java/io/substrait/examples/util/SubstraitStringify.java
@@ -67,6 +67,7 @@ public class SubstraitStringify extends ParentStringify
 
   private boolean showRemap = false;
 
+  /** Constructor. */
   public SubstraitStringify() {
     super(0);
   }
@@ -96,7 +97,7 @@ public static List<String> explain(io.substrait.plan.Plan plan) {
   /**
    * Explains the Sustrait relation
    *
-   * @param plan Subsrait relation
+   * @param rel Subsrait relation
    * @return List of strings; typically these would then be logged or sent to stdout
    */
   public static List<String> explain(io.substrait.relation.Rel rel) {
diff --git a/examples/substrait-spark/src/main/java/io/substrait/examples/util/TypeStringify.java b/examples/substrait-spark/src/main/java/io/substrait/examples/util/TypeStringify.java
index 0e13c3e2e..d09e79a3a 100644
--- a/examples/substrait-spark/src/main/java/io/substrait/examples/util/TypeStringify.java
+++ b/examples/substrait-spark/src/main/java/io/substrait/examples/util/TypeStringify.java
@@ -29,10 +29,15 @@
 import io.substrait.type.Type.VarChar;
 import io.substrait.type.TypeVisitor;
 
-/** TypeStringify produces a simple debug string of Substrait types */
+/** TypeStringify produces a simple debug string of Substrait types. */
 public class TypeStringify extends ParentStringify
     implements TypeVisitor<String, RuntimeException> {
 
+  /**
+   * Constructor.
+   *
+   * @param indent numver of idents to use
+   */
   protected TypeStringify(int indent) {
     super(indent);
   }
diff --git a/isthmus-cli/build.gradle.kts b/isthmus-cli/build.gradle.kts
index db96206b3..724a08fc7 100644
--- a/isthmus-cli/build.gradle.kts
+++ b/isthmus-cli/build.gradle.kts
@@ -97,3 +97,10 @@ tasks.register("writeIsthmusVersion") {
 }
 
 tasks.named("compileJava") { dependsOn("writeIsthmusVersion") }
+
+tasks.named<Javadoc>("javadoc") {
+  description = "Generate Javadoc for main source files (excludes generated)."
+
+  val isthmusVersionClass = layout.buildDirectory.file("generated/sources").get().getAsFile()
+  exclude { spec -> spec.file.toPath().startsWith(isthmusVersionClass.toPath()) }
+}
diff --git a/isthmus-cli/src/main/java/io/substrait/isthmus/cli/InitializeAtBuildTime.java b/isthmus-cli/src/main/java/io/substrait/isthmus/cli/InitializeAtBuildTime.java
index 01c35b535..a80396dbf 100644
--- a/isthmus-cli/src/main/java/io/substrait/isthmus/cli/InitializeAtBuildTime.java
+++ b/isthmus-cli/src/main/java/io/substrait/isthmus/cli/InitializeAtBuildTime.java
@@ -1,3 +1,4 @@
 package io.substrait.isthmus.cli;
 
+/** */
 public class InitializeAtBuildTime {}
diff --git a/isthmus-cli/src/main/java/io/substrait/isthmus/cli/IsthmusEntryPoint.java b/isthmus-cli/src/main/java/io/substrait/isthmus/cli/IsthmusEntryPoint.java
index 35d5c6ed2..02c363967 100644
--- a/isthmus-cli/src/main/java/io/substrait/isthmus/cli/IsthmusEntryPoint.java
+++ b/isthmus-cli/src/main/java/io/substrait/isthmus/cli/IsthmusEntryPoint.java
@@ -23,6 +23,7 @@
 import picocli.CommandLine.Option;
 import picocli.CommandLine.Parameters;
 
+/** Isthmus CLI entry point. */
 @Command(
     name = "isthmus",
     versionProvider = io.substrait.isthmus.cli.IsthmusCliVersion.class,
@@ -61,6 +62,11 @@ enum OutputFormat {
       description = "Calcite's casing policy for unquoted identifiers: ${COMPLETION-CANDIDATES}")
   private Casing unquotedCasing = Casing.TO_UPPER;
 
+  /**
+   * Standard Java Main method.
+   *
+   * @param args Isthmus CLI arguments.
+   */
   public static void main(String... args) {
     CommandLine commandLine = new CommandLine(new IsthmusEntryPoint());
     commandLine.setCaseInsensitiveEnumValuesAllowed(true);
diff --git a/isthmus-cli/src/main/java/io/substrait/isthmus/cli/RegisterAtRuntime.java b/isthmus-cli/src/main/java/io/substrait/isthmus/cli/RegisterAtRuntime.java
index 266a36ff0..4dd1070ba 100644
--- a/isthmus-cli/src/main/java/io/substrait/isthmus/cli/RegisterAtRuntime.java
+++ b/isthmus-cli/src/main/java/io/substrait/isthmus/cli/RegisterAtRuntime.java
@@ -45,6 +45,7 @@
 import org.graalvm.nativeimage.hosted.RuntimeReflection;
 import org.immutables.value.Value;
 
+/** */
 public final class RegisterAtRuntime implements Feature {
   @Override
   public void beforeAnalysis(BeforeAnalysisAccess access) {