[pkg/ottl] Fix issue with named parameter spacing (open-telemetry#28511)

**Description:** 
Fixes an issue with the grammar where named parameters had to have a
space after the `=`.

**Link to tracking Issue:**
Closes
open-telemetry#27638

**Testing:** 
Added a new unit test

Author: TylerHelmuth

.chloggen/ottl-fix-named-param-spacing.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: pkg/ottl
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix bug where named parameters needed a space after the equal sign (`=`).
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [28511]
+
+# (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:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# 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: []

pkg/ottl/grammar.go

@@ -434,14 +434,14 @@ func buildLexer() *lexer.StatefulDefinition {
 		{Name: `Float`, Pattern: `[-+]?\d*\.\d+([eE][-+]?\d+)?`},
 		{Name: `Int`, Pattern: `[-+]?\d+`},
 		{Name: `String`, Pattern: `"(\\"|[^"])*"`},
-		{Name: `Equal`, Pattern: `=[^=]`},
 		{Name: `OpNot`, Pattern: `\b(not)\b`},
 		{Name: `OpOr`, Pattern: `\b(or)\b`},
 		{Name: `OpAnd`, Pattern: `\b(and)\b`},
 		{Name: `OpComparison`, Pattern: `==|!=|>=|<=|>|<`},
 		{Name: `OpAddSub`, Pattern: `\+|\-`},
 		{Name: `OpMultDiv`, Pattern: `\/|\*`},
 		{Name: `Boolean`, Pattern: `\b(true|false)\b`},
+		{Name: `Equal`, Pattern: `=`},
 		{Name: `LParen`, Pattern: `\(`},
 		{Name: `RParen`, Pattern: `\)`},
 		{Name: `Punct`, Pattern: `[,.\[\]]`},

pkg/ottl/parser_test.go

@@ -1059,6 +1059,24 @@ func Test_parse(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:      "editor with named arg",
+			statement: `set(name="foo")`,
+			expected: &parsedStatement{
+				Editor: editor{
+					Function: "set",
+					Arguments: []argument{
+						{
+							Name: "name",
+							Value: value{
+								String: ottltest.Strp("foo"),
+							},
+						},
+					},
+				},
+				WhereClause: nil,
+			},
+		},
 	}
 
 	for _, tt := range tests {