ESQL: Fix compilation

Two PR passing in the night, break each other.

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/ip/IpPrefix.java

@@ -78,12 +78,12 @@ public class IpPrefix extends EsqlScalarFunction implements OptionalArgument {
     }
 
     public static IpPrefix readFrom(PlanStreamInput in) throws IOException {
-        return new IpPrefix(in.readSource(), in.readExpression(), in.readExpression(), in.readExpression());
+        return new IpPrefix(Source.readFrom(in), in.readExpression(), in.readExpression(), in.readExpression());
     }
 
-    public static void writeTo(PlanStreamOutput out, IpPrefix ipPrefix) throws IOException {
-        out.writeSource(ipPrefix.source());
-        List<Expression> fields = ipPrefix.children();
+    public void writeTo(PlanStreamOutput out) throws IOException {
+        source().writeTo(out);
+        List<Expression> fields = children();
         assert fields.size() == 3;
         out.writeExpression(fields.get(0));
         out.writeExpression(fields.get(1));

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/io/stream/PlanNamedTypes.java

@@ -395,7 +395,7 @@ public final class PlanNamedTypes {
             of(ScalarFunction.class, DateTrunc.class, PlanNamedTypes::writeDateTrunc, PlanNamedTypes::readDateTrunc),
             of(ScalarFunction.class, E.class, PlanNamedTypes::writeNoArgScalar, PlanNamedTypes::readNoArgScalar),
             of(ScalarFunction.class, Greatest.class, PlanNamedTypes::writeVararg, PlanNamedTypes::readVarag),
-            of(ScalarFunction.class, IpPrefix.class, IpPrefix::writeTo, IpPrefix::readFrom),
+            of(ScalarFunction.class, IpPrefix.class, (out, prefix) -> prefix.writeTo(out), IpPrefix::readFrom),
             of(ScalarFunction.class, Least.class, PlanNamedTypes::writeVararg, PlanNamedTypes::readVarag),
             of(ScalarFunction.class, Log.class, PlanNamedTypes::writeLog, PlanNamedTypes::readLog),
             of(ScalarFunction.class, Now.class, PlanNamedTypes::writeNow, PlanNamedTypes::readNow),