diff --git a/.baseline/checkstyle/checkstyle.xml b/.baseline/checkstyle/checkstyle.xml
index 2f1bfe81..494192ad 100644
--- a/.baseline/checkstyle/checkstyle.xml
+++ b/.baseline/checkstyle/checkstyle.xml
@@ -1,15 +1,9 @@
-<?xml version="1.0"?>
-<!DOCTYPE module PUBLIC
-        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
-        "https://checkstyle.org/dtds/configuration_1_3.dtd">
-
-<!--
+<?xml version="1.0" encoding="UTF-8" standalone="no"?><!--
     Palantir Baseline Checkstyle configuration.
     Authors: Robert Fink, Brian Worth, Merrick Zoubeiri, and many other contributors. Based in part on http://checkstyle.sourceforge.net/google_style.html
     Please keep checks alphabetized with one exception: "relaxed" checks are grouped together at the bottom for easier disabling.
     Check-specific comments reference documents internal to Palantir and can be safely ignored or removed.
- -->
-
+ --><!DOCTYPE module PUBLIC "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN" "https://checkstyle.org/dtds/configuration_1_3.dtd">
 <module name="Checker">
     <property name="charset" value="UTF-8"/>
     <property name="severity" value="error"/>
@@ -47,6 +41,10 @@
     <module name="BeforeExecutionExclusionFileFilter">
         <property name="fileNamePattern" value="module\-info\.java$"/>
     </module>
+    <module name="LineLength"> <!-- Java Style Guide: No line-wrapping -->
+        <property name="max" value="120"/>
+        <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
+    </module>
     <module name="TreeWalker">
         <module name="SuppressionCommentFilter"/> <!-- baseline-gradle: README.md -->
         <module name="SuppressionCommentFilter">
@@ -77,14 +75,7 @@
         </module>
         <module name="AvoidStarImport"/> <!-- Java Style Guide: No wildcard imports -->
         <module name="AvoidStaticImport"> <!-- Java Style Guide: No static imports -->
-            <property name="excludes" value="
-                com.google.common.base.Preconditions.*,
-                com.palantir.logsafe.Preconditions.*,
-                java.util.Collections.*,
-                java.util.stream.Collectors.*,
-                org.apache.commons.lang3.Validate.*,
-                org.assertj.core.api.Assertions.*,
-                org.mockito.Mockito.*"/>
+            <property name="excludes" value="com.google.common.base.Preconditions.*, com.palantir.logsafe.Preconditions.*, java.util.Collections.*, java.util.stream.Collectors.*, org.apache.commons.lang3.Validate.*, org.assertj.core.api.Assertions.*, org.mockito.Mockito.*"/>
         </module>
         <module name="ClassTypeParameterName"> <!-- Java Style Guide: Type variable names -->
             <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
@@ -134,12 +125,12 @@
         <module name="IllegalImport"> <!-- Java Coding Guidelines: Import the canonical package -->
             <property name="id" value="BanShadedClasses"/>
             <property name="illegalPkgs" value=".*\.(repackaged|shaded|thirdparty)"/>
-            <property name="regexp" value="true" />
+            <property name="regexp" value="true"/>
             <message key="import.illegal" value="Must not import repackaged classes."/>
         </module>
         <module name="IllegalImport">
             <property name="illegalPkgs" value="^org\.gradle\.(internal|.*\.internal)"/>
-            <property name="regexp" value="true" />
+            <property name="regexp" value="true"/>
             <message key="import.illegal" value="Do not rely on gradle internal classes as these may change in minor releases - use org.gradle.api versions instead."/>
         </module>
         <module name="IllegalImport">
@@ -192,11 +183,9 @@
             <property name="separated" value="true"/>
             <property name="sortStaticImportsAlphabetically" value="true"/>
         </module>
+        
         <module name="InnerAssignment"/> <!-- Java Coding Guidelines: Inner assignments: Not used -->
-        <module name="LineLength"> <!-- Java Style Guide: No line-wrapping -->
-            <property name="max" value="120"/>
-            <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
-        </module>
+         <!-- Java Style Guide: Nonempty blocks: K & R style -->
         <module name="MemberName"> <!-- Java Style Guide: Non-constant field names -->
             <property name="format" value="^[a-z][a-zA-Z0-9]+$"/>
             <message key="name.invalidPattern" value="Member name ''{0}'' must match pattern ''{1}''."/>
@@ -237,6 +226,7 @@
             <message key="name.invalidPattern" value="Package name ''{0}'' must match pattern ''{1}''."/>
         </module>
         <module name="ParameterAssignment"/> <!-- Java Coding Guidelines: Final variables and parameters -->
+         <!-- Java Style Guide: Horizontal whitespace -->
         <module name="RedundantImport"/> <!-- Java Style Guide: No unused imports -->
         <module name="RedundantModifier"/> <!-- Java Coding Guidelines: Avoid redundant modifiers -->
         <module name="RegexpSinglelineJava"> <!-- Java Coding Guidelines: Use appropriate assertion methods -->
@@ -352,7 +342,7 @@
         </module>
         <module name="RegexpSinglelineJava">
             <property name="format" value="\bCharset.defaultCharset\("/>
-            <property name="message" value="Use explicit charset (e.g. StandardCharsets.UTF-8) instead of default."/>
+            <property name="message" value="Use explicit charset (e.g. StandardCharsets.UTF_8) instead of default."/>
         </module>
         <module name="RegexpSinglelineJava">
             <property name="format" value="\bIOUtils\.toString\("/>
@@ -361,6 +351,7 @@
         <module name="RegexpSinglelineJava">
             <property name="format" value="\/\/TODO|\/\/ TODO(?!\([^()\s]+\): )"/>
             <property name="message" value="TODO format: // TODO(#issue): explanation"/>
+            <property name="ignoreCase" value="true"/>
         </module>
         <module name="RegexpSinglelineJava">
             <property name="format" value="(void setUp\(\))|(void setup\(\))|(void setupStatic\(\))|(void setUpStatic\(\))|(void beforeTest\(\))|(void teardown\(\))|(void tearDown\(\))|(void beforeStatic\(\))|(void afterStatic\(\))"/>
@@ -368,11 +359,11 @@
         </module>
         <module name="RightCurly"> <!-- Java Style Guide: Nonempty blocks: K & R style -->
             <property name="option" value="same"/>
-            <property name="tokens" value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_DO"/>
+            <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_DO"/>
         </module>
         <module name="RightCurly"> <!-- Java Style Guide: Nonempty blocks: K & R style -->
             <property name="option" value="alone"/>
-            <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT, INSTANCE_INIT"/>
+            <property name="tokens" value="LITERAL_FOR, LITERAL_WHILE, STATIC_INIT, INSTANCE_INIT"/>
         </module>
         <module name="SeparatorWrap"> <!-- Java Style Guide: Where to break -->
             <property name="tokens" value="DOT"/>
@@ -390,7 +381,7 @@
         <module name="SuppressWarnings">
             <property name="format" value="serial"/>
         </module>
-        <module name="SuppressWarningsHolder" />  <!-- Required for SuppressWarningsFilter -->
+        <module name="SuppressWarningsHolder"/>  <!-- Required for SuppressWarningsFilter -->
         <module name="TypeName"> <!-- Java Style Guide: Class names -->
             <message key="name.invalidPattern" value="Type name ''{0}'' must match pattern ''{1}''."/>
         </module>
@@ -401,16 +392,7 @@
         <module name="UpperEll"/> <!-- Java Style Guide: Numeric Literals -->
         <module name="VisibilityModifier"/> <!-- Java Coding Guidelines: Minimize mutability -->
         <module name="WhitespaceAfter"/> <!-- Java Style Guide: Horizontal whitespace -->
-        <module name="WhitespaceAround"> <!-- Java Style Guide: Horizontal whitespace -->
-            <property name="allowEmptyConstructors" value="true"/>
-            <property name="allowEmptyMethods" value="true"/>
-            <property name="allowEmptyTypes" value="true"/>
-            <property name="allowEmptyLoops" value="true"/>
-            <property name="allowEmptyLambdas" value="true"/>
-            <property name="ignoreEnhancedForColon" value="false"/>
-            <message key="ws.notFollowed" value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
-            <message key="ws.notPreceded" value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
-        </module>
+        
 
         <!-- Stricter checks begin: delete some or all of the following for faster prototyping, but please restore before pushing to production. -->
 
@@ -423,13 +405,10 @@
             <property name="ignoredAnnotations" value="ParameterizedTest, Test, Before, BeforeEach, After, AfterEach, BeforeClass, BeforeAll, AfterClass, AfterAll"/>
         </module>
         <module name="JavadocMethod"> <!-- Java Style Guide: Where Javadoc is used -->
-            <property name="scope" value="public"/>
+            <property name="accessModifiers" value="public"/>
             <property name="allowMissingParamTags" value="true"/>
-            <property name="allowMissingThrowsTags" value="true"/>
             <property name="allowMissingReturnTag" value="true"/>
-            <property name="minLineCount" value="99999999"/>
             <property name="allowedAnnotations" value="Override, Test"/>
-            <property name="allowThrowsTagsForSubclasses" value="true"/>
         </module>
         <module name="JavadocStyle"/> <!-- Java Style Guide: Javadoc -->
         <module name="JavadocTagContinuationIndentation"> <!-- Java Style Guide: At-clauses -->
@@ -462,4 +441,4 @@
 
         <!-- Stricter checks end -->
     </module>
-</module>
+</module>
\ No newline at end of file
diff --git a/.baseline/idea/intellij-java-palantir-style.xml b/.baseline/idea/intellij-java-palantir-style.xml
index 945d8bad..f41e2b8a 100644
--- a/.baseline/idea/intellij-java-palantir-style.xml
+++ b/.baseline/idea/intellij-java-palantir-style.xml
@@ -44,6 +44,18 @@
               <package name="" withSubpackages="true" static="false" />
             </value>
           </option>
+          <DO_NOT_IMPORT_INNER>
+            <CLASS name="Builder" />
+            <CLASS name="Callback" />
+            <CLASS name="Class" />
+            <CLASS name="Entry" />
+            <CLASS name="Enum" />
+            <CLASS name="Factory" />
+            <CLASS name="Type" />
+            <CLASS name="Key" />
+            <CLASS name="Id" />
+            <CLASS name="Provider" />
+          </DO_NOT_IMPORT_INNER>
         </GroovyCodeStyleSettings>
         <option name="JD_ALIGN_EXCEPTION_COMMENTS" value="false" />
         <option name="JD_ALIGN_PARAM_COMMENTS" value="false" />
diff --git a/build.gradle b/build.gradle
index 14b62195..b1a7df89 100644
--- a/build.gradle
+++ b/build.gradle
@@ -9,7 +9,7 @@ buildscript {
         classpath 'com.palantir.javaformat:gradle-palantir-java-format:1.0.1'
         classpath 'com.gradle.publish:plugin-publish-plugin:0.15.0'
         classpath 'com.palantir.gradle.consistentversions:gradle-consistent-versions:2.0.0'
-        classpath 'com.palantir.baseline:gradle-baseline-java:3.23.0'
+        classpath 'com.palantir.baseline:gradle-baseline-java:4.9.0'
         classpath 'com.palantir.gradle.conjure:gradle-conjure:5.10.0'
         classpath 'com.palantir.gradle.gitversion:gradle-git-version:0.12.3'
         classpath 'gradle.plugin.org.inferred:gradle-processors:3.3.0'
diff --git a/gradle-metric-schema/src/main/java/com/palantir/metric/schema/gradle/CreateMetricsManifestTask.java b/gradle-metric-schema/src/main/java/com/palantir/metric/schema/gradle/CreateMetricsManifestTask.java
index 33c03e3b..d548ce41 100644
--- a/gradle-metric-schema/src/main/java/com/palantir/metric/schema/gradle/CreateMetricsManifestTask.java
+++ b/gradle-metric-schema/src/main/java/com/palantir/metric/schema/gradle/CreateMetricsManifestTask.java
@@ -185,14 +185,13 @@ private static Optional<List<MetricSchema>> inferProjectDependencyMetrics(Projec
         return Optional.of(ObjectMappers.loadMetricSchema(file));
     }
 
-    private static java.util.Optional<List<MetricSchema>> getExternalMetrics(
-            ComponentIdentifier id, ResolvedArtifact artifact) {
+    private static Optional<List<MetricSchema>> getExternalMetrics(ComponentIdentifier id, ResolvedArtifact artifact) {
         if (!artifact.getFile().exists()) {
             log.debug("Artifact did not exist: {}", artifact.getFile());
-            return java.util.Optional.empty();
+            return Optional.empty();
         } else if (!Files.getFileExtension(artifact.getFile().getName()).equals("jar")) {
             log.debug("Artifact is not jar: {}", artifact.getFile());
-            return java.util.Optional.empty();
+            return Optional.empty();
         }
 
         try {
@@ -200,12 +199,11 @@ private static java.util.Optional<List<MetricSchema>> getExternalMetrics(
             ZipEntry manifestEntry = zipFile.getEntry(MetricSchemaPlugin.METRIC_SCHEMA_RESOURCE);
             if (manifestEntry == null) {
                 log.debug("Manifest file does not exist in JAR: {}", id);
-                return java.util.Optional.empty();
+                return Optional.empty();
             }
 
             try (InputStream is = zipFile.getInputStream(manifestEntry)) {
-                return java.util.Optional.of(
-                        ObjectMappers.mapper.readValue(is, new TypeReference<List<MetricSchema>>() {}));
+                return Optional.of(ObjectMappers.mapper.readValue(is, new TypeReference<List<MetricSchema>>() {}));
             }
         } catch (IOException e) {
             throw new RuntimeException("Failed to load external monitors");
diff --git a/metric-schema-java/src/main/java/com/palantir/metric/schema/JavaGeneratorArgs.java b/metric-schema-java/src/main/java/com/palantir/metric/schema/JavaGeneratorArgs.java
index abc7cab3..2fd66b98 100644
--- a/metric-schema-java/src/main/java/com/palantir/metric/schema/JavaGeneratorArgs.java
+++ b/metric-schema-java/src/main/java/com/palantir/metric/schema/JavaGeneratorArgs.java
@@ -24,6 +24,8 @@
 import java.util.regex.Pattern;
 import org.immutables.value.Value;
 
+// Automatically suppressed to unblock enforcement in new code
+@SuppressWarnings("ImmutablesStyle")
 @Value.Immutable
 @Value.Style(
         visibility = Value.Style.ImplementationVisibility.PACKAGE,
diff --git a/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Namespace.java b/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Namespace.java
index 7b8c94de..fe9f9b0f 100644
--- a/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Namespace.java
+++ b/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Namespace.java
@@ -21,6 +21,8 @@
 import com.palantir.metric.schema.MetricNamespace;
 import org.immutables.value.Value;
 
+// Automatically suppressed to unblock enforcement in new code
+@SuppressWarnings("ImmutablesStyle")
 @Value.Immutable
 @Value.Style(
         overshadowImplementation = true,
diff --git a/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Section.java b/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Section.java
index 14fd42c2..3311cee9 100644
--- a/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Section.java
+++ b/metric-schema-markdown/src/main/java/com/palantir/metric/schema/markdown/Section.java
@@ -21,6 +21,8 @@
 import java.util.List;
 import org.immutables.value.Value;
 
+// Automatically suppressed to unblock enforcement in new code
+@SuppressWarnings("ImmutablesStyle")
 @Value.Immutable
 @Value.Style(
         overshadowImplementation = true,