[filter] unexport CombinedFilter (open-telemetry#10348)

#### Description
Unexport CombinedFilter, it should not be exported as it implements
Filter.

.chloggen/filter.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: deprecation
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: filter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Deprecate the `filter.CombinedFilter` struct
+
+# One or more tracking issues or pull requests related to the change
+issues: [10348]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [api]

filter/config.go

@@ -8,7 +8,7 @@ import (
 	"regexp"
 )
 
-// Config configures the matching behavior of a FilterSet.
+// Config configures the matching behavior of a Filter.
 type Config struct {
 	Strict string `mapstructure:"strict"`
 	Regex  string `mapstructure:"regexp"`
@@ -32,14 +32,17 @@ func (c Config) Validate() error {
 	return nil
 }
 
-type CombinedFilter struct {
+type combinedFilter struct {
 	stricts map[any]struct{}
 	regexes []*regexp.Regexp
 }
 
-// CreateFilter creates a Filter from yaml config.
+// Deprecated: [v0.103.0] This type will be removed in the future.
+type CombinedFilter combinedFilter
+
+// CreateFilter creates a Filter out of a set of Config configuration objects.
 func CreateFilter(configs []Config) Filter {
-	cf := &CombinedFilter{
+	cf := &combinedFilter{
 		stricts: make(map[any]struct{}),
 	}
 	for _, config := range configs {
@@ -56,7 +59,7 @@ func CreateFilter(configs []Config) Filter {
 	return cf
 }
 
-func (cf *CombinedFilter) Matches(toMatch any) bool {
+func (cf *combinedFilter) Matches(toMatch any) bool {
 	_, ok := cf.stricts[toMatch]
 	if ok {
 		return ok