Properly map List -> list and Map -> dict for ApiExporter

Starlark.fromJava() converts these into their Starlark equivalents.

PiperOrigin-RevId: 511823824
Change-Id: If35f8d5f3327b8bae19d75e100c468da4fafc024

src/main/java/com/google/devtools/build/docgen/starlark/StarlarkJavaMethodDoc.java

@@ -126,7 +126,7 @@ public String getReturnTypeExtraMessage() {
 
   @Override
   public String getReturnType() {
-    return Starlark.classType(method.getReturnType());
+    return Starlark.classTypeFromJava(method.getReturnType());
   }
 
   @Override

src/main/java/net/starlark/java/eval/Starlark.java

@@ -411,6 +411,42 @@ public static String classType(Class<?> c) {
     }
   }
 
+  /**
+   * Returns the name of the type of instances of {@code c} after being converted to Starlark values
+   * by {@link #fromJava}, or "unknown" for {@code Object.class}, since that is used as a wildcard
+   * type by evaluation machinery.
+   *
+   * <p>Note that {@code void.class} is treated as "NoneType" since void methods will return None to
+   * Starlark.
+   *
+   * @throws InvalidStarlarkValueException if {@code c} is not {@code Object.class} and {@link
+   *     #fromJava} would throw for instances of {@code c}.
+   */
+  public static String classTypeFromJava(Class<?> c) {
+    if (c.equals(
+            void.class) // Method.invoke on void-returning methods returns null; we treat it as None
+        || c.equals(String.class)
+        || c.equals(boolean.class)
+        || c.equals(Boolean.class)
+        || StarlarkValue.class.isAssignableFrom(c)
+        || c.equals(Object.class)) {
+      return classType(c);
+    } else if (c.equals(int.class)
+        || c.equals(Integer.class)
+        || c.equals(long.class)
+        || c.equals(Long.class)
+        || BigInteger.class.isAssignableFrom(c)) {
+      return classType(StarlarkInt.class);
+    } else if (c.equals(double.class) || c.equals(Double.class)) {
+      return classType(StarlarkFloat.class);
+    } else if (List.class.isAssignableFrom(c)) {
+      return classType(StarlarkList.class);
+    } else if (Map.class.isAssignableFrom(c)) {
+      return classType(Dict.class);
+    }
+    throw new InvalidStarlarkValueException(c);
+  }
+
   /**
    * The ordering relation over (some) Starlark values.
    *