Add Java support to custom code regions documentation

docs/customize/code/code-regions/java.mdx

@@ -0,0 +1,105 @@
+---
+title: Custom code regions in Java
+description: "Learn how to use custom code regions in Java SDKs."
+---
+
+# Custom code regions in Java
+
+To enable custom code regions for Java SDKs, update the project's
+`.speakeasy/gen.yaml` file like so:
+
+```diff .speakeasy/gen.yaml
+configVersion: 2.0.0
+generation:
+  # ...
+java:
+  # ...
++ enableCustomCodeRegions: true
+```
+
+## Full example
+
+The Speakeasy examples repository has a [full example](https://github.com/speakeasy-api/examples/tree/main/customcode-sdkclasses-java) of a Java SDK
+that uses custom code regions.
+
+
+## Regions
+
+Below are the available code regions in Java SDKs.
+
+### SDK classes
+
+Java SDK classes can have two code regions:
+
+* `// #region imports` - allows the addition of imports to an SDK file needed for
+custom methods and properties. This region must be located at the top of the
+file alongside generated imports.
+* `// #region sdk-class-body` - allows the addition of custom methods and
+properties to an SDK class. This region must be located in the body of a Java
+SDK class alongside generated methods and properties.
+
+## Managing dependencies
+
+When adding custom code that requires external packages, configure these dependencies in the `.speakeasy/gen.yaml` file to prevent them from being removed during SDK regeneration. Use the `additionalDependencies` configuration to specify package dependencies:
+
+```yaml .speakeasy/gen.yaml
+java:
+  additionalDependencies:
+    - implementation:org.commonmark:commonmark:0.21.0
+    - implementation:org.jsoup:jsoup:1.16.1
+    - testImplementation:org.junit.jupiter:junit-jupiter:5.9.2
+    - testImplementation:org.mockito:mockito-core:5.1.1
+```
+
+This ensures dependencies persist across SDK regenerations and are properly included in the generated `build.gradle`.
+
+```java src/main/java/com/example/sdk/Todos.java
+/*
+ * Code generated by Speakeasy (https://speakeasy.com). DO NOT EDIT.
+ */
+
+package com.example.sdk;
+
+import com.example.sdk.models.operations.*;
+import com.example.sdk.models.shared.*;
+import com.example.sdk.utils.HTTPClient;
+import com.example.sdk.utils.HTTPRequest;
+import com.example.sdk.utils.Utils;
+
+// !focus(1:3)
+// #region imports
+import org.commonmark.parser.Parser;
+import org.commonmark.renderer.html.HtmlRenderer;
+// #endregion imports
+
+public class Todos implements
+            MethodCallCreate,
+            MethodCallGetOne {
+
+    private final SDKConfiguration sdkConfiguration;
+
+    Todos(SDKConfiguration sdkConfiguration) {
+        this.sdkConfiguration = sdkConfiguration;
+    }
+
+    // !focus(1:11)
+    // #region sdk-class-body
+    public String renderTodo(String id) throws Exception {
+        Todo todo = getOne(id).todo()
+            .orElseThrow(() -> new Exception("Todo not found"));
+
+        Parser parser = Parser.builder().build();
+        HtmlRenderer renderer = HtmlRenderer.builder().build();
+
+        String markdown = String.format("# %s\n\n%s", todo.title(), todo.description());
+
+        return renderer.render(parser.parse(markdown));
+    }
+    // #endregion sdk-class-body
+
+    public Todo getOne(String id) throws Exception {
+        // Generated method implementation
+        ...
+    }
+}
+```

docs/customize/code/code-regions/overview.mdx

@@ -36,5 +36,6 @@ for [creating code folds](https://code.visualstudio.com/docs/editor/codebasics#_
 
 Custom code regions are currently supported in the following languages:
 
+- [Java](/docs/customize/code/code-regions/java)
 - [Python](/docs/customize/code/code-regions/python)
 - [TypeScript](/docs/customize/code/code-regions/typescript)