@Override
                                protected void doVisit(Expression e) {
                                    if (e instanceof EmbedExpression ee) {
                                        ee.requestedEmbedderId().ifPresent(id -> {
                                            var fieldName = field.getName();
                                            var schemaName = schema.fullSchema().getName();
                                            log.log(Level.FINE, () -> "Found embedder '%s' for field '%s' in schema '%s'".formatted(id, fieldName, schemaName));
                                            fieldToEmbedderId.put(new SchemaAndField(schemaName, fieldName), id);
                                        });
                                    }
                                }
Validates that all embedder ids specified in 'embed' expressions references an existing component.

@author bjorncs
config-model/src/main/java/com/yahoo/vespa/model/application/validation/EmbedExpressionValidator.java