fix: review comments

Signed-off-by: MBWhite <whitemat@uk.ibm.com>

Author: mbwhite

isthmus/src/main/java/io/substrait/isthmus/expression/FunctionConverter.java

@@ -158,6 +158,10 @@ public FunctionConverter(
 
   /**
    * Resolves a Calcite {@link SqlOperator} from a Substrait function key (Substrait → Calcite).
+   * <p>
+   * Given a Substrait function key (e.g., "concat:str_str") and output type, this method finds
+   * the corresponding Calcite {@link SqlOperator}. When multiple operators match, the output type
+   * is used to disambiguate.
    *
    * @param key Substrait function key (e.g., {@code concat:str_str})
    * @param outputType expected Substrait output type used for disambiguation

isthmus/src/main/java/io/substrait/isthmus/expression/FunctionMappings.java

@@ -16,8 +16,6 @@
  * <p>Also provides type-based resolvers to disambiguate operators by output type.
  */
 public class FunctionMappings {
-  // Static list of signature mapping between Calcite SQL operators and Substrait base function
-  // names.
 
   /** Scalar operator signatures mapped to Substrait function names. */
   public static final ImmutableList<Sig> SCALAR_SIGS =
@@ -139,7 +137,7 @@ public class FunctionMappings {
           .addAll(AGGREGATE_SIGS)
           .build();
 
-  // contains return-type based resolver for both scalar and aggregator operator
+  
   /** Type-based resolvers to disambiguate Calcite operators by expected output type. */
   public static final Map<SqlOperator, TypeBasedResolver> OPERATOR_RESOLVER =
       Map.of(
@@ -169,7 +167,7 @@ public static void main(String[] args) {
    * Creates a signature mapping entry.
    *
    * @param operator the Calcite operator
-   * @param substraitName the Substrait base function name
+   * @param substraitName the Substrait canonical function name
    * @return a {@link Sig} instance
    */
   public static Sig s(SqlOperator operator, String substraitName) {

isthmus/src/main/java/io/substrait/isthmus/expression/IgnoreNullableAndParameters.java

@@ -221,10 +221,9 @@ public Boolean visit(Type.UUID type) {
    *
    * @param type user-defined type
    * @return {@code true} if {@code typeToMatch} equals {@code type}
-   * @throws RuntimeException if comparison cannot be performed
    */
   @Override
-  public Boolean visit(Type.UserDefined type) throws RuntimeException {
+  public Boolean visit(Type.UserDefined type) {
     // Two user-defined types are equal if they have the same uri AND name
     return typeToMatch.equals(type);
   }

isthmus/src/main/java/io/substrait/isthmus/sql/SubstraitSqlDialect.java

@@ -49,7 +49,7 @@ public SubstraitSqlDialect(Context context) {
   /**
    * Indicates whether this dialect supports approximate COUNT(DISTINCT) operations.
    *
-   * @return {@code true}, as Substrait SQL dialect supports approximate count distinct.
+   * @return akways {@code true}, as Substrait SQL dialect supports approximate count distinct.
    */
   @Override
   public boolean supportsApproxCountDistinct() {